Brigitte Gabriel claimed:
"He (Prophet Muhammad peace be upon him) started preaching in his own  city Mecca. He tried to recruit sons and followers to spread his  religion and he tried for twelve years and failed. And after twelve  years he was only able to recruit his immediate family and friends. So  he decided if I go to Medina, which was the Jewish hub of Arabia, the  business hub where the Jews lived: If I go there and preach my religion  to them if they respect me that will buy me respect and stature with my own people who will then respect me."
The truth is that the Prophet and his people were tortured, murdered and eventually they  were forcefully exiled out of Makkah. Even when the Muslims settled to  get on with their lives they were still hunted down to be killed just  for abandoning their former polytheistic faith:
 
Persecutions
Having fully perceived that Muhammad (Peace be upon  him) could   never be desisted from his Call, Quraish, in a desperate  attempt to quell the   tidal wave of the Call, resorted to other cheap  means acting from base motives:
 
 [*=left]                     Scoffing, degrading, ridiculing, belying and  laughter-instigating cheap   manners, all of which levelled at the new  converts in general, and the person of   Muhammad (Peace be upon him) in  particular, with the aim of dragging the spirit   of despair  into their morale, and slackening their ardent zealotry. They used to    denounce the Prophet (Peace be upon him) as a man possessed by a jinn,  or an   insane person:
And they say: O you [Muhammad (Peace be upon him) ] to whom the Dhikr (the Qur'an) has been sent down! Verily, you are a mad man. [15:6]        
 
 or a liar practising witchcraft, 
  
  And they (Arab pagans) wonder that a warner  [Prophet Muhammad   (Peace be upon him) ] has come to them from among  themselves! And the   disbelievers say: This [Prophet Muhammad (Peace be  upon him) ] is a sorcerer, a   liar. [38:4].        
 
 Their eyes would also look at the good man as  if they would eat   him up ' , or trip him up, or disturb him from the  position of stability or   firmness. They used all sorts of terms of  abuse madman' or one possessed by an   evil spirit', and so on: 
  
  And verily, those who disbelieve would almost  make you slip   with their eyes through hatreds when they hear the  Reminder (the Qur'an), and   they say: Verily, he [Muhammad (Peace be  upon him) ] is a madman!   [68:51]        
  
  Amongst the early converts, there was a group  who had   unfortunately no strong clan at their back to support them.  These innocent souls   were ridiculed and jeered in season and out of  season. Referring to such people,   the highbrow Quraish aristocrats  used repeatedly to ask the Prophet (Peace be   upon him), with jest and  scorn: 
  
  Allah has favoured from amongst us? [6:53]            
  
  And Allah said: 
  
  Does not Allah know best those who are grateful?   [6:53]        
  
  The wicked used to laugh at the righteous in many ways:
 [*=left]           They would inwardly laugh at their Faith, because they felt themselves so   superior.
 [*=left]           In public places, when the righteous passed, they used to insult and wink at   them,
 [*=left]           In their own houses, they would run them down.
 [*=left]           Whenever and wherever they saw them, they reproached and  called them fools   who had lost their way. In the Hereafter, all these  tricks and falsehoods will   be shown for what they are, and the tables  will be reversed. Allâh had said:
        Verily! (During the worldly life)  those who committed crimes   used to laugh at those who believed; and  whenever they passed by them, used to   wink one to another (in  mockery); and when they returned to their own people,   they would  return jesting; and when they saw them, they said: Verily! These have    indeed gone astry!' But they (disbelievers, sinners) had not been sent  as   watchers over them (the believers). [83:29-33]
 [*=left]                     Distorting Muhammad's teachings, evoking  ambiguities, circulating false   propaganda; forging groundless  allegations concerning his doctrines, person and   character, and going  to excess in such a manner in order to screen off any scope   of sound  contemplation from the public. With respect to the Qur'an, they used to   allege that it was:
Tales of the ancients, which he [Muhammad  (Peace be upon him) ]   has written down, and they are dictated to him  morning and afternoon.   [25:5]              
 
 The iniquitous went on ceaselessly inculcating in people's ears   that the Qur'an was not a true Revelation: 
  
  This (the Qur'an) is nothing but a lie  that he [Muhammad (Peace   be upon him) ] has invented, and others have  helped him at it.   [25:4]        
  
  The wicked would also attribute to men  of Allâh just such   motives and springs of action as they themselves  would be guilty of in such   circumstances. The pagans and those who  were hostile to the revelation of Allâh   and Islam, could not  understand how such wonderful verses could flow from the   tongue of the  Prophet (Peace be upon him) without having someone to teach, and    claimed: 
  
  It is only a human being who teaches him.   [16:103] 
 
 They also raised another baseless and superficial objection: 
  
  Why does this Messenger [Muhammad (Peace  be upon him) ] eat   food and walk about in the markets (like  ourselves)? [25:7]              
 
 They were sadly ignorant and painfully  at fault for they could   not perceive that a teacher for mankind is one  who shares their nature, mingles   intheir life, is acquainted with  their doings, and sympathises with their joys   and sorrows. 
The Noble Qur'an has vehemently refuted their  charges and   allegations and has explained that the utterances of the  Prophet (Peace be upon   him) are the Revelations of the Lord and their  nature and contents provide a   bold challenge to those who attribute  his Prophetic expressions to some base   origin, at times to the mental  throes of a dreaming reformer, at others to the   effusion of a frenzied  poet or the incoherent drivelling of an insane man.
 [*=left]           Contrasting the Qur'an with the mythology of the ancients in order to   distract people's interests from Allâh's Words.  Once An-Nadr bin Harith   addressed the Quraishites in the following  manner: O Quraish! You have   experienced an unprecedented phenomenon  before which you have so far been   desperately helpless. Muhammad  (Peace be upon him) grew up here among you and   always proved to be  highly obliging, the most truthful and trustworthy young   man. However,  later on when he reached manhood, he began to preach a new faith    alien to your society, and opposed to your liking so you began to  denounce him   at a time as a sorcerer, at another as a soothsayer, a  poet, or even an insane   man. I swear by Allâh he is not anyone of  those. He is not interested in blowing   on knots as magicians are, nor  do his words belong to the world of soothsaying;   he is not a poet  either, for his mentality is not that of a rambler, nor is he   insane  because he has never been witnessed to develop any sort of  hallucinations   or insinuations peculiar to madmen. O people of  Quraish, it is really a serious   issue and I recommend that you  reconsider your attitude.
It is narrated that An-Nadr, at a later  stage, headed for   Heerah where he got conversant with the traditions  of the kings of Persia and   the accounts of people like Rustum and  Asphandiar, and then returned to Makkah.   Here he would always shadow  the Messenger's steps in whatever audiences the   later held to preach  the new faith and to caution people against Allâh's wrath.   An-Nadr  would directly follow the Prophet (Peace be upon him) and narrate to the    same audience long tales about those people of Persia. He would then  always   append his talk with a question cunningly inquiring if he did  not outdo Muhammad   (Peace be upon him). Ibn Abbas (May Allah be  pleased with him) related that   An-Nadr used to purchase songstresses  who would through their bodily charms and   songs entice away from Islam  anyone developing the least attachment to the   Prophet (Peace be upon  him); in this regard, Allâh says:
And of mankind is he who purchases idle talks (i.e. music,   singing, etc.) to mislead (men) from the Path of Allâh. [31:6]
 [*=left]            In a fresh attempt to dissuade Muhammad (Peace be upon him)  from his   principled stand, Quraish invited him to compromise on his  teachings and come to   terms with their pre-Islamic practices in such a  way that he quits some of his   religion and the polytheists do the  same. Allâh, the All-High says:
They wish that you should compromise (in  religion out of   courtesy) with them, so they (too) would compromise  with you. [68:9].              
 
 On the authority of Ibn Jareer and  At-Tabarani, the idolaters   offered that Muhammad (Peace be upon him)  worship their gods for a year, and   they worship his Lord for a year.  In another version, they said: If you accept   our gods, we would  worship yours. Ibn Ishaq related that Al-Aswad bin   Al-Muttalib,  Al-Waleed bin Al-Mugheerah, Omaiyah bin Khalaf and Al-As bin Wa'il    As-Sahmy, a constellation of influential polytheists, intercepted the  Prophet   (Peace be upon him) while he was circumambulating in the Holy  Sanctuary, and   offered him to worship that they worshipped, and they  worship that he worshipped   so that, according to them, both parties  would reach a common denominator. They   added Should the Lord you  worship prove to be better than ours, then it will be   so much better  for us, but if our gods proved to be better than yours, then you   would  have benefit from it. Allâh, the Exalted, was decisive on the spot and    revealed the following Chapter:
Say: O 
Al-Kâfirûn (disbelievers in Allâh, in His   Oneness, in His Angels, in His Books, in His Messengers, in the Day of   Resurrection, in 
Al-Qadar,  etc.)! I worship not that which you worship,   nor will you worship  that which I worship. And I shall not worship that which   you are  worshipping, nor will you worship that which I worship. To you be your    religion, and to me my religion (Islamic Monotheism).(
Safy Arrahman, the sealed nectar)
  
The failed plot:
 
Now that all the schemes and conspiracof Quraish had failed, they  resorted to their old practices of persecution and inflicting tortures  on the Muslims in a more serious and brutal manner than ever before.  They also began to nurse the idea of killing the Prophet (Peace be upon  him). In fact, contrary to their expectations, this new method and this  very idea served indirectly to consolidate the Call to Islam and support  it with the conversion of two staunch and mighty heroes of Makkah, i.e.  Hamzah bin 'Abdul-Muttalib and 'Umar bin Al-Khattab (May Allah be  pleased with him).
 
 THE FIRST ‘AQABAH PLEDGE
 
 Six Madinese who embraced Islam in the pilgrimage season in the eleventh  year of Prophethood. They promised to communicate the Message of Islam  to their townsfolk.
 
 The following year, on the occasion of the pilgrimage, there came a  group of twelve disciples ready to acknowledge Muhammad as their  Prophet.   They avowed their faith in Muhammad (Peace be upon him) as a Prophet and  swore: “We will not worship any one but one Allah; we will not steal;  neither will we commit adultery, nor kill our children; we will not  utter slander, intentionally forging falsehood and we will not disobey  you in any just matter.” When they had taken the pledge, Muhammad (Peace  be upon him) said: “He who carries it out, Allâh will reward him; and  who neglects anything and is afflicted in this world, it may prove  redemption for him in the Hereafter; and if the sin remains hidden from  the eyes of the men and no grief comes to him, then his affair is with  Allâh. He may forgive him or He may not.”
 
 THE MUSLIM ENVOY IN MADINAH:
 
 After the Pledge (in the form of an oath had been taken) the Prophet (Peace be upon him) sent to Yathrib (Madinah) Mus‘ab bin ‘Umair  Al-‘Abdari, (May Allah be pleased with him)  the first Muslim  ‘ambassador’ to teach the people there the doctrines of Islam, give them  practical guidance and make attempts at propagating the Islam among  those who still professed polytheism.
 
 The Second   ‘Aqabah Pledge
 The next year, thirteenth of Prophethood, June 622 A.D., during the  pilgrimage season, over seventy converts from Madinah came in the trail  of their polytheist people to perform the rituals of pilgrimage in  Makkah. The oft-repeated question amongst them was “Isn’t it high time we protect Muhammad instead of leaving him forsaken, deserted and stumbling in the hillocks of Makkah?”
 
 "Prophet Muhammad (peace be upon him) started borrowing a lot from the old testament, to make his religion more palpable to the Jews: To make it a lot similar. This is why you saw a lot of similarities between Judaism and Islam. For example: Jews don't eat pigs, Muslims don't eat pigs. Jews pray few times a day, Muslims pray few times a day. Jews fast on Yon-Kipper, Muslims fast on Ramadan."
Answer:
The simple fact that Prophet Muhammad (peace be upon him) was illiterate, actually refutes her whole notion. However, let's examine this in more details:
Many critics allege that Prophet Muhummad (pbuh) learnt quran and/or adapted it from previous scriptures or revelations. This has been refuted by muslims; See 
this refutation by Zakir Naik, but now we will focus only on some points: 
 
It is true that the Prophet did have religious discussions with the Jews but they took place in Madinah more than 13 years after the revelation of the Qur’an had started. The allegation that these Jews  were the source is perverse, since in these discussions Prophet Muhammad (pbuh) was performing 
the roles of a teacher and of a preacher while inviting them to embrace Islam and pointing out that they had deviated from their true teachings of Monotheism. Several of these Jews later embraced Islam. 
All historical records available show that Muhummad (pbuh) had made only three trips outside Makkah before his Prophethood: 
At the age of 9 he accompanied his mother to Madinah.
Between the age of 9 and 12, he accompanied his uncle Abu-Talib on a business trip to Syria.
At the age of 25 he led Khadija’s Caravan to Syria.
It is highly imaginary to assume that the Qur’an resulted from the occasional chats and meetings with the Christians or Jews from any of the above three trips. 
[h=2]LOGICAL GROUNDS[/h]The day-to-day life of the Prophet was an open book for all to see. In fact a revelation came asking people to give the Prophet (pbuh) privacy in his own home. If the Prophet had been meeting people who told him what to say as a revelation from God, this would not have been hidden for very long.
The extremely prominent Quraish nobles who followed the Prophet and accepted Islam were wise and intelligent men who would have easily noticed anything suspicious about the way in which the Prophet brought the revelations to them - more so since the Prophetic mission lasted 23 years.
 
The enemies of the Prophet kept a close watch on him in order to find proof for their claim that he was a liar - they could not point out even a single instance when the Prophet may have had a secret rendezvous with particular Jews.
It is inconceivable that any human author of the Qur’an would have accepted a situation in which he received no credit whatsoever for originating the Qur’an. 
Thus, historically and logically it cannot be established that there was a human source for the Qur’an. 
[h=2]MUHUMMAD (PBUH) WAS AN ILLITERATE[/h]The theory that Muhummad (pbuh) authored the Qur’an or copied from other sources can be disproved by the single historical fact that he was illiterate.
Allah testifies Himself in the Qur’an
In Surah Al-Ankabut chapter no.29 verse 48 
"And thou was not (able) to recite a Book before this (Book came), nor art thou (able) to transcribe it with thy right hand: in that case, indeed, would the talkers of vanities have doubted."
[Al-Qur’an 29:48]
Allah (swt) knew that many would doubt the authenticity of the Qur’an and would ascribe it to Prophet Muhummad (pbuh). Therefore Allah in His Divine Wisdom chose the last and final Messenger to be an ‘Ummi’, i.e. unlettered, so that the talkers of vanity would not then have the slightest justification to doubt the Prophet. The accusation of his enemies that he had copied the Qur’an from other sources and rehashed it all in a beautiful language might have carried some weight, but even this flimsy pretence has been deprived to the unbeliever and the cynic. 
Allah reconfirms in the Qur’an in Surah Al A’raf chapter 7 verse 157: 
"Those who follow the Messenger, the unlettered Prophet, whom they find mentioned in their own (Scriptures) in the Law and the Gospel"
The prophecy of coming of the unlettered Prophet (pbuh) is also mentioned in the Bible in the book of Isaiah chapter 29 verse 12.
"And the book is delivered to him that is not learned."
[Isaiah 29:12]
The Qur’an testifies in no less than four different places that the Prophet (pbuh) was illiterate. It is also mentioned in Surah A’raf chapter 7 verse 158 and in Surah Al-Jumu’a chapter 62 verse 2. 
[h=2]SIMILARITIES IN THE QUR’AN AND OT ARE DUE TO COMMON SOURCE[/h]Similarities between the Qur’an and the Bible does not necessarily mean that the former has been copied from the latter. In fact it gives evidence that both of them are based on a common third source; all divine revelations came from the same source - the one universal God. No matter what human changes were introduced into some of these Judeo-Christian and other older religious scriptures that had distorted their originality, there are some areas that have remained free from distortion and thus are common to many religions.
It is true that there are some similar parallels between the Qur’an and the Bible but this is not sufficient to accuse Muhummad (pbuh) of compiling or copying from the Bible. The same logic would then also be applicable to teachings of Christianity and Judaism and thus one could wrongly claim that Jesus (pbuh) was not a genuine Prophet (God forbid) and that he simply copied from the Old Testament.
The similarities between the two signify a common source that is one true God and the continuation of the basic message of monotheism and not that the later prophets have plagiarised from the previous prophets.
If someone copies during an examination he will surely not write in the answer sheet that he has copied from his neighbour or Mr. XYZ. Prophet Muhummad (pbuh) gave due respect and credit to all the previous prophets (pbut). The Qur’an also mentions the various revelations given by Almighty God to different prophets. 
[h=2]MUSLIMS BELIEVE IN THE TAURAH, ZABOOR, INJEEL AND QUR’AN[/h]Four revelations of Allah (swt) are mentioned by name in the Qur’an: the Taurah, the Zaboor, the Injeel and the Qur’an.
Taurah, the revelation i.e. the Wahi given to Moosa (a. s.) i.e. Moses (pbuh).
Zaboor, the revelation i.e. the Wahi given to Dawood (a.s.) i.e. David (pbuh).
Injeel, the revelation i.e. the Wahi given to Isa (A.S.) ie. Jesus (pbuh).
‘Al-Qur’an’, the last and final Wahi i.e. revelation given to the last and final Messenger Muhammad (pbuh).
It is an article of faith for every Muslim to believe in all the Prophets of God and all revelations of God. However, the present day Bible has the first five books of the Old Testament attributed to Moses and the Psalms attributed to David. Moreover the New Testament or the four Gospels of the New Testament are not the Taurah, the Zaboor or the Injeel, which the Qur’an refers to. These books of the present day Bible may partly contain the word of God but these books are certainly not the exact, accurate and complete revelations given to the prophets.
The Qur’an presents all the different prophets of Allah as belonging to one single brotherhood; all had a similar prophetic mission and the same basic message. Because of this, the fundamental teachings of the major faiths cannot be contradictory, even if there has been a considerable passage of time between the different prophetic missions, because the source of these missions was one: Almighty God, Allah. This is why the Qur’an says that the differences which exist between various religions are not the responsibility of the prophets, but of the followers of these prophets who forgot part of what they had been taught, and furthermore, misinterpreted and changed the scriptures. The Qur’an cannot therefore be seen as a scripture which competes with the teachings of Moses, Jesus and the other prophets. On the contrary, it confirms, completes and perfects the messages that they brought to their people. 
Another name for the Qur’an is the ‘The Furqan’ which means the criteria to judge the right from the wrong, and it is on the basis of the Qur’an that we can decipher which part of the previous scriptures can be considered to be the word of God. 
 
[h=2]QUR’AN IS A BOOK FROM ALLAH[/h]These evidences are sufficient to conclude that the Qur’an was not copied from the Bible, but that the Qur’an is the Furqaan - ‘the Criteria’ to judge right from wrong and it should be used to decipher which portion of the Bible may be considered as the Word of God.
The Qur’an itself testifies in Surah Sajda chapter 32 verse 1 to 3
Alif Laam Meem.
(This is) the revelation of the Book in which there is no doubt – from the Lord of the Worlds.
Or do they say, ‘He has forged it’? Nay, it is the Truth from thy Lord, that thou mayest admonish a people to whom no warner has come before thee: in order that they may receive guidance." [Al-Qur’an 32:1-3]
[h=2]More palatable to Jews ?![/h]
Quran clearly states those who die while not believing that “There is no true god but God, and Muhammad is the Messenger (Prophet) of God” or are not Muslim will lose Paradise forever and will be sent to Hellfire, as God has said:
" And whoever seeks a religion other than Islam, it will not be accepted from him and he will be one of the losers in the Hereafter. " (Quran, 3:85)
And as He has said:
" Those who have disbelieved and died in disbelief, the earth full of gold would not be accepted from any of them if it were offered as a ransom.  They will have a painful punishment, and they will have no helpers. " (Quran, 3:91)
God is very clear in this aspect. 
http://islamic-life-forum.blogspot.com/2017/02/re-brigitte-gabriela-brief-history-of_20.html