Hello zzz1234 and welcome to the forum,
Despite wanting to join Islam, as a Christian believing Jesus was crucified and resurrected my whole life is something very hard to quit believing in. Are there not eye witness accounts for the crucifixion? It's not that I'm reluctant to let my views go, it's just difficult.
If we say that someone else was crucified in the place of Jesus :as:, that would mean regardless of whether there were eye witness accounts or not, it would not prove it was Jesus :as: who died on the cross. We've had some discussions in the past on the crucifixion - the points discussed therein might be of use to you:
http://www.islamicboard.com/comparative-religion/12656-crucifixion.html
http://www.islamicboard.com/comparative-religion/2392-paradox-resurrection.html
http://www.islamicboard.com/clarifications-about-islam/134322981-crucifixion-quran.html
http://www.islamicboard.com/comparative-religion/1022-invalidity-crucifixion-jesus.html
The transition from Christianity to Islam may not be as difficult as you think. That is because as a Muslim you will continue to believe in, respect and love Jesus :as:, as with all the Prophets sent by God:
Islam is the only non-Christian religion which makes it an article of faith to believe in the central figure of Christianity, i.e. Jesus Christ (peace be upon him). If a person calls himself a Muslim and doesn't believe in, respect, or love Jesus (peace be upon him) then he is NOT a Muslim. NO other religion has this stipulation.
We believe that Jesus (peace be upon him) was one of the mightiest messengers of God.
We believe that he was the messiah, translated as christ.
We believe he was born miraculously without any male intervention, which many modern day Christians today do not believe.
We believe that he gave life to the dead with Gods permission.
We believe he healed those born blind and lepers with Gods permission
However we don't believe that Jesus ever claimed divinity, or that he was God, son of God, or that he said worship me. We also do not believe that he was crucified.
We believe in all prophets whether we have heard of them or not. That includes the final Prophet Muhammad (peace be upon him). We are not allowed to pick and choose those we believe in. We also believe in the existence of all the books of God i.e. Bible, Torah, Psalms of David (peace be upon him), and any other books that we have not been told about, revealed before our time. We also believe in the angels, and day of judgement.
Some of the reverts from Christianity have said on this very forum that:
I know one question I frequently get asked is how could a seminarian ever leave Christianity. Oddly, I feel that the more I learned about Isa(as) the more I was led to search for the truth and that search eventually brought me to Islam. I believe I finally found Jesus(as) through Islam and that the truth is much more beautiful than what I had been taught.
to add... there were books written like "Imitation of Christ"... and other similar to it which we have come across in the seminary. And if we really seek and observe the way of life of Issah (Aleihi Salaam) - it is no different than a real Muslim.
Regarding your other question:
Also, despite performing the 5 daily prayers and going to mosque on Fridays, what else should I be doing as a Muslim?
God has taught us that He created us in order to worship Him. The teachings of Islam give guidance in all aspects of what we do. By striving to follow that, seeking God's pleasure, we will be successful.
God has placed upon us certain obligations and prohibitions we must strive to fulfil. The greatest of all that God has commanded is Tawheed, which is to single out God with all worship. The most serious thing He forbade is Shirk, which is to invoke others besides Him, along with Him. Acts of worship include prayer (for men, they should strive to pray their daily prayers in congregation at the Mosque, not only on Fridays). Other key acts of worship include obligatory charity (Zakah), fasting and pilgrimage for those who are able. Moreover, we have responsibilities towards other people such as our parents, relatives and the poor. The following verse from the Qur'an lists some of these, starting with the most important:
Worship Allah and join none with Him (in worship); and do good to parents, kinsfolk, orphans, Al-Masakin (the poor), the neighbour who is near of kin, the neighbour who is a stranger, the companion by your side, the wayfarer (you meet), and those (slaves) whom your right hands possess. Verily, Allah does not like such as are proud and boastful. [Qur'an 4:36]
Other passages in the Qur'an similarly mention what is required of us:
Say (O Muhammad صلى الله عليه وسلم): "Come, I will recite what your Lord has prohibited you from: Join not anything in worship with Him; be good and dutiful to your parents; kill not your children because of poverty - We provide sustenance for you and for them; come not near to Al-Fawahish (shameful sins, illegal sexual intercourse) whether committed openly or secretly; and kill not anyone whom Allah has forbidden, except for a just cause (according to Islamic law). This He has commanded you that you may understand.
"And come not near to the orphan's property, except to improve it, until he (or she) attains the age of full strength; and give full measure and full weight with justice. We burden not any person, but that which he can bear. And whenever you give your word (i.e. judge between men or give evidence), say the truth even if a near relative is concerned, and fulfil the Covenant of Allah. This He commands you, that you may remember .
"And verily, this is My Straight Path, so follow it, and follow not (other) paths, for they will separate you away from His Path. This He has ordained for you that you may become Al-Muttaqun (the pious)." [Qur'an 6: 151-153]
We are also taught in Islam that all human acts are acts of worship if they are done for God alone and in accordance to His Divine Law. As such, worship in Islam is not limited to religious rituals. The teachings of Islam act as a mercy and a healing for the human soul, and such qualities as humility, sincerity, patience and benevolence are strongly encouraged.
I hope this has helped to give you some idea. There is much to learn but the key is to start slow and gradually learn more. Start with the basics and most important things, and go from there. In-sha-Allah (God Willing) you will gain a much better understanding over time.
May Allaah :swt: open your heart to the light of Islam, guide you and make this step easy for you, Aameen.
