It’s great that you are asking questions. We should never be afraid to search for the truth. 1 John 4:1 says"Beloved, do not believe every spirit, but test the spirits to see whether they are from God, for many false prophets have gone out into the world."
The central figure in Islam is Muhammad, born around 570AD in Mecca. He was into spending a lot of time in caves for seclusion and meditation, often fasting and prone to dreams. Around that time and in that area there were potential influences on Muhammad from Judaism, Monophysite Christianity, Nestorian Christianity (both of which had unbiblical views about the divine and human nature of Jesus) and hermits from the Byzantine Church (which was of Roman Catholic persuasion).
The Islamic religion is based on a series of ‘recitations’ that this one man, Muhammad, was said to have received from an angel sent from God over the years 610-632AD. At first he wasn’t sure whether these were divine or demonic, but his wife encouraged him to believe they were from God. These recitations were written by scribes on pieces of cloth, leather, bone, stone etc. and some were kept by oral tradition, at the time they happened. So any account of Jesus is from a recitation written or remembered at the time the ‘revelation’ happened, not, of course, at the time of Jesus. After Muhammad’s death in 632AD, these recitations were gathered together over the period between 633AD and about 650AD and compiled into one book, the Qur’an. There seems to be no particular order in the compilation- it’s not chronological nor is it by subject matter. The Qur’an is held by Muslims to be the final and only uncorrupted word from God available. The lens through which the Qur’an is read by most Muslims is the hadiths, which is a collection of deeds and sayings of Muhammad, handed down by oral tradition and written some 200 years after his death.
Muslims believe that Allah is the creator of the universe and that he is the God of Abraham (i.e. the same as Yahweh, the God of Jews and Christians). Muslims do consider the Tawrat (by Moses, which is the Torah or the whole Old Testament depending on the particular Islamic understanding), the Zabur (which is the book of Psalms but includes Ruth), and the Injil (the lost gospel given to Jesus, or the current gospels or the whole New Testament depending again on the particular Islamic understanding) to be holy books, but all are considered to have been corrupted. Muslims believe that the Qur’an confirms and corrects these corrupted biblical narrations.
While Jesus is held to be a prophet from God, the Qur’an says that he wasn’t crucified and didn’t die-
Qur’an 4:157-8 says-
157. And their saying: Surely we have killed the Messiah, Isa (Jesus) son of Marium (Mary), the apostle of Allah (God); and they did not kill him nor did they crucify him, but it appeared to them so (like Isa) and most surely those who differ therein are only in a doubt about it; they have no knowledge respecting it, but only follow a conjecture, and they killed him not for sure.
158. Nay! Allah (God) took him up to Himself; and Allah (God) is Mighty, Wise.
There is no evidence to support this ‘revelation’ except to the Muslim who believes that the Qur’an is the word of God. All reliable historical research, both Christian and secular, support the death of Jesus, and by crucifixion, with the gospels regarded highly as an historical source for both Christian and secular historians.
It is true that the gospels were written some years after the events. The earliest is Mark written sometime between 65-75AD. The lateness of these dates need not be a concern when it’s understood that in these times there was an oral tradition (where people tended to learn by, and trust more, what they heard than what they read, as with some of the Qur’an). Remember too that Jesus died around 31-33AD and so ‘late’ is not really that late. There were false stories being spread around even at the beginning (see Matt 28:11-15), but these gospels were written from eye witnesses and their accounts, and when there were still eye witnesses around who could have easily refuted them if they were false (Matthew 27:54-56, Mark 15:39-41, Luke 1:2, Luke 23:47-49, John 19:25-27, John 20:24-28, Acts 10:34-43, 1Cor 15:3-8, 2Peter 1:16-2:3, ). In addition, Jesus trusted the authority of the Old Testament, and so by his authority his followers trust it too (see Matt 5:17-18).
There is also extensive non-biblical and non-Christian evidence written by Jewish and non-Jewish people at the time that point to the existence, influence and (in particular) death of Jesus by crucifixion. I don’t have enough space here to go into this but you could have a look at The Christ Files for further information about this evidence and the historical accuracy of the biblical evidence.
There is also a unity and cohesiveness in the Old and New Testaments where all prophecies by many prophets over centuries point to Christ. The big picture is a sovereign and personal God drawing a people to himself, saved from the punishment they deserve for their sins by his taking this punishment on himself in Christ, and destined to live under his gracious rule in his perfect kingdom. All other religions require their followers to work their way to heaven. In Christ Jesus, all the saving work is done by God.
Jesus’ authority can be understood in the miracles he performed (John 14:11) and by his death, resurrection and ascension as reported by eye-witnesses and of which Jesus also prophesied (Mark 10:33-34). There is no miracle credited to Muhammad except the Qur’an which, it can be argued, is not a miracle.
Broadly speaking, we are left with two options:
1) Do we trust that the ‘prophecies’ of one man about Jesus are reliable when he was influenced by fringe expressions of Christianity and Judaism, some distance away from the events and some 600 years later, and despite contradicting other historical evidence?
2) Do we trust in the prophecies of several people over many centuries and the historically reliable eye-witness accounts of several others who all point to Jesus as the Christ and saviour of the world, as backed up by his teaching, miracles and resurrection from the dead?
There are a couple of books which I really recommend. The first is"Islam In Our Backyard" by Tony Payne, which looks both into Islam and truth. The second is"The Christ Files" by John Dickson (as I mentioned above), which looks into how historians know what they know about Jesus. Both books are relatively short and quite readable.
I hope and pray this helps and that your trust in the work of Jesus on your behalf will be strengthened.