I think the following article by Dr Zakir Naik will clear your confusion:statisfie
When all the Muslim follow one and the same Qur’an then why are there so many sects and different schools of thoughts among Muslims?
Answer:
1. Muslims Should be United
It is a fact that Muslims today, are divided amongst themselves. The tragedy is that such divisions are not endorsed by Islam at all. Islam believes in fostering unity amongst its followers. The Glorious Qur’an says:
"And hold fast, All together, by the rope Which Allah (stretches out for you), and be not divided among yourselves;" [Al-Qur’an 3:103]
Which is the rope of Allah that is being referred to in this verse? It is the Glorious Qur’an. The Glorious Qur’an is the rope of Allah which all Muslims should hold fast together. There is double emphasis in this verse. Besides saying ‘hold fast all together’ it also says, ‘be not divided’. Qur’an further says,
"Obey Allah, and obey the Messenger" [Al-Qur’an 4:59]
All the Muslim should follow the Qur’an and authentic Ahadith and be not divided among themselves.
2. It is Prohibited to make sects and divisions in Islam
The Glorious Qur’an says:
"As for those who divide Their religion and break up Into sects, thou hast No part in them in the least: Their affair is with Allah: He will in the end Tell them the truth Of all that they did." [Al-Qur’an 6:159]
In this verse Allah (swt) says that one should disassociate oneself from those who divide their religion and break it up into sects. But when one asks a Muslim, "who are you?", the common answer is either ‘I am a Sunni, or ‘I am a Shia’. Some call themselves Hanafi, or Shafi or Maliki or Humbali. Some say ‘I am a Deobandi’, while some others say ‘I am a Barelvi’.
3. Our Prophet was a Muslim
One may ask such Muslims, "Who was our beloved prophet (pbuh)? Was he a Hanafi or a Shafi, or a Humbali or a Maliki?" No! He was a Muslim, like all the other prophets and messengers of Allah before him. It is mentioned in chapter 3 verse 52 of Al-Qur’an that Jesus (pbuh) was a Muslim. Further, in chapter 3 verse 67, Al-Qur’an says that Ibrahim (pbuh) was not a Jew or a Christian but was a Muslim.
4. Qur’an says call yourselves Muslim
If anyone poses a Muslim the question who are you, he should say "I am a MUSLIM, not a Hanafi or a Shafi". Surah Fussilat chapter 41 verse 33 says "Who is better in speech Than one who calls (men) To Allah, works righteousness, And says, ‘I am of those Who bow in Islam (Muslim)?’ " [Al-Qur’an 41:33]
The Qur’an says "Say I am of those who bow in Islam". In other words, say, "I am a Muslim".
The Prophet (pbuh) dictated letters to non-Muslim kings and rulers inviting them to accept Islam. In these letters he mentioned the verse of the Qur’an from Surah Ali Imran chapter 3 verse 64: Say ye:
"Bear witness That we (at least) Are Muslims (bowing To Allah’s Will)." [Al-Qur’an 3:64]
5. Respect all the Great Scholars of Islam
We must respect all the great scholars of Islam, including the four Imaams, Imam Abu Hanifa, Imam Shafi, Imam Humbal and Imam Malik (may Allah be pleased with them all). They were great scholars and may Allah reward them for their research and hardwork. One can have no objection if someone agrees with the views and research of Imam Abu Hanifa or Imam Shafi, etc. But when posed a question, ‘who are you?’, the reply should only be
‘I am a Muslim’.
Some may argue by quoting the hadith of our beloved Prophet from Sunan Abu Dawood Hadith No. 4579. In this hadith the prophet (pbuh) is reported to have said,
"My community will be split up into seventy-three sects." This hadith reports that the prophet predicted the emergence of seventy-three sects. He did not say that Muslims should be active in dividing themselves into sects. The Glorious Qur’an commands us not to create sects.
Those who follow the teachings of the Qur’an and Sahih Hadith, and do not create sects are the people who are on the true path.
According to Tirmidhi Hadith No. 171, the prophet (pbuh) is reported to have said,
"My Ummah will be fragmented into seventy-three sects, and all of them will be in Hell fire except one sect." The companions asked Allah’s messenger which group that would be. Where upon he replied, "It is the one to which I and my companions belong." The Glorious Qur’an mentions in several verses,
"Obey Allah and obey His Messenger". A true Muslim should only follow the Glorious Qur’an and the Sahih Hadith. He can agree with the views of any scholar as long as they conform to the teachings of the Qur’an and Sahih Hadith. If such views go against the Word of Allah, or the Sunnah of His Prophet, then they carry no weight, regardless of how learned the scholar might be.
If only all Muslims read the Qur’an with understanding and adhere to Sahih Hadith, Inshallah most of these differences would be solved and we could be one united Muslim Ummah.
Source
www.irf.net , Lectures by Dr Zakir Naik.