The collection of the New Testament Books, my Muslim friend

It is an established fact that the books of the New Testament were collected before the death of John the Apostle. Therefore, he was able to see and approve these books. As for the charge that the original books were changed or replaced by others, we would say that Christians scholars and laymen from time of the Apostle John until the present watched over them with utmost care. Christian theologians have occupied a position similar to that of the tribe of Levi whom God set apart for the preservation and promotion of the law of Moses. They devoted themselves to expounding, interpreting and preaching these books. They zealously guarded them because they regarded the Bible as one of the means to their soul's salvation: "So then faith comes by hearing and hearing by the Word of God" (Romans 10:17). Is it any wonder that the Bible were translated and transmitted with utmost care in an unbroken chain of authority from one generation to the next?