The Quran - perfectly preserved and unaltered
I would like to mention in passing that in contrast to the compilation of the New Testament and specifically the Gospels of Matthew, Mark, Luke and John, the Quran, which is one book, was revealed in its entirety to one prophet, Mohammed. It was memorized by many of his followers as it was received over a period of 23 years and was also written down during Mohammed’s lifetime. It was definitively transcribed within two decades of Mohammed’s death and verified by his closest surviving companions. Two of the four copies of the original Quran made at that time are still in existence - one in Istanbul in Turkey, the other in Tashkent in Uzbekistan in former Soviet central Asia. Every Arabic Qur’an in the world today is, letter for letter, identical to this ancient script.
Indeed, in the 19th century, an institute of Munich University in Germany collected a staggering forty-two thousand different copies of the Quran including manuscripts and printed texts produced in various parts of the Islamic world over a period spanning thirteen hundred years. Research work was carried out on these texts for half a century, at the end of which the researchers concluded that apart from copying mistakes, there was no discrepancy in the text of these forty-two thousand copies, even though they were produced at different times between the first and fourteenth Islamic centuries and had been procured from all parts of the world. Unfortunately this institute and its priceless treasure of Quranic manuscripts were destroyed in an Allied bombing attack on Germany during World War II, but the findings of its research project survived.
In short, the Quran stands or falls as one. The integrity of the text itself is above reproach. There remains only a personal decision whether to accept it or not as the word of God.
In addition to the Quran, the ahadeeth, or sayings of Prophet Mohammed, which form the secondary strand of Islamic scripture, were meticulously collected and authenticated by the second Islamic century by Muslim scholars who only accepted a given saying as genuine if it had a proven chain of trustworthy transmitters stretching back to one or more original companion of the Prophet. Many thousands of plausible sayings were rejected if they did not meet these strict criteria.
Doubts about Jesus’s divinity even within the Gospels
Even within the four canonical Gospels there are numerous passages which cast doubt on the divinity of Jesus and therefore on the concept of Trinity which presupposes it. There are at least twenty instances where Jesus prays. See Matthew 14:23, 19:13, 26:39, 27:46, 26:42-44; Mark 1:35, 6:46, 14:35-36; Luke 3:21, 5:16, 6:12, 9:18, 9:28, 11:1-4, 22:41; John 14:16, 17:1, 17:9, 17:11, 17:15. If Jesus were himself divine, i.e. God, to whom is he praying and why?
Consider also these passages:
Jesus and God had different wills.
Matthew 19:16-17, Mark 10:17-18 and Luke 18:18-19.
Jesus denied divinity by distinguishing between himself and God.
Luke 7:16, 13:33, 24:19; John 4:19
Jesus was regarded by his disciples and other contemporaries as a prophet. They do not acclaim him as an incarnation of God or the Son of God.
My Journey from Catholic Christian to Arian Unitarian to Muslim
As a result of my studies and after much soul-searching, I came to reject Pauline church doctrinal innovations such as the Trinity, a concept unknown to Jesus’ disciples and not definitively established as official church doctrine until as late as 381A.D. I found myself in sympathy with the more purely monotheist beliefs of the late third and early fourth century priest Arius of Alexandria and others such as Bishop Eusebius of Nicomedia (later Patriarch of Constantinople), their teacher, the respected priest and martyr Lucian of Antioch and, in later decades, Roman Emperor Constantius II. The Catholic Encyclopaedia defines Arianism as:
“a heresy which arose in the fourth century, and denied the divinity of Jesus Christ,... not a modern form of unbelief, and [it] therefore will appear strange in modern eyes.”
What the encyclopaedia fails to mention is that what they are describing as heresy was, in fact, official church doctrine in the middle of the fourth century. For example, after the Council of Ariminum (present-day Rimini in Italy) in 359A.D. St. Jerome wrote, “the whole world groaned and marvelled to find itself Arian”. This prevailed until after the death of Constantius II and his fellow Arian successors when a changing political climate within the Roman Empire resulted in the persecution of Arian Christians and the conclusive imposition of Trinitarianism as official church doctrine at the Second General Council in 381A.D.
When I too came to the conclusion that Jesus was not divine, I had crossed an essential hurdle in terms of mindset and beliefs. Whether or not Jesus is divine is the absolute crux of the matter as far as any believing, theologically aware Christian is concerned. Once I had come to this new understanding of Jesus, it was but a small step for me to be able to accept a later prophet and embrace Islam, just as the North African and Iberian Arian Christians, denounced by the Church but physically safe outside the shrinking borders of the Roman Empire, had done en masse when Islam was introduced to them in the decades after the death of Mohammed. Because of my Christian upbringing, I was used to the concept of God sending prophets periodically throughout history at times when mankind had fallen away from His teachings. Islam recognizes the Old Testament prophets I was familiar with plus John the Baptist and Jesus. Given that, by the seventh century, Arabia had lapsed into polytheism and much of the Christian world was Trinitarian, it made sense to me that God should send a new prophet, Mohammed, to call mankind back to the correct worship of Himself, the one true god.
There are 25 prophets recognized by name in the Quran. All but three of them are also mentioned in Jewish or Christian scripture:
2) Idrís (Idrees)
3) Núh (Noah)
6) Ibráhím (Abraham)
7) Ismá’íl (Ishmael)
8) Isháq (Isaac)
9) Lút (Lot)
10) Ya’qúb (Jacob)
11) Yúsuf (Joseph)
13) Ayúb (Job)
14) Músa (Moses)
15) Hárún (Aaron)
16) Dhu l-kifl (Ezzekiel)
17) Dawúd (David)
19) Ilyás (Elijah)
20) al-Yasa’ (Elisha)
21) Yúnus (Jonas)
22) Zakaríya (Zakariyah)
23) Yahyá (John the Baptist)
24) ‘Ísa (Jesus)
I had now reached the point where I genuinely wanted to be a Muslim in my own right, whether my interest in the Muslim lady mentioned previously led to marriage or not. (In fact the relationship in question eventually did not work out.) For I see my conversion to Islam not as a rejection of what I regard as true Christianity, simply as a rejection of the tangent or erroneous path along which Paul and his followers led astray the new, gentile, former polytheistic Christians of the Greco-Roman world. Sadly, all major forms of modern Christianity - Roman Catholicism, Eastern Orthodoxy and Protestantism - stem from Paul.
The Catholic Encyclopaedia states that Arianism has never been revived (although it concedes that such eminent figures as Sir Isaac Newton and Milton displayed Arian sympathies). What it fails to acknowledge is that Arianism has, for the last fourteen hundred years, been incorporated within Islam. There is no one left within Catholicism, Protestantism or Orthodoxy to espouse the oneness of God. The reason why Trinitarianism now rules unfettered within the greatly reduced geographical boundaries of old world Christendom is that the peoples of all the southern Mediterranean formerly Arian Christian strongholds are now overwhelmingly Muslim!
 Catholic Encyclopaedia