How can it be claimed that the Gospel has been corrupted, given the existence of verses affirming its preservation and a stern warning to those who corrupt it, and who benefits from this corruption, and why is the Qur'an described as contradictory, and is what the Prophet Muhammad says not new?

In response to your claim that the Qur'an is full of contradictions, we say that no one is incapable of insults. Yet the Qur'an remains, with its influence, guidance, miraculousness, and its ability to silence opponents. Allah Almighty says: "And if it had been from [any] other than Allah, they would have found within it much contradiction." The Prophet (peace be upon him) only stated that Jesus is a servant of Allah and His messenger, His word which He directed to Mary, and a spirit created by Him. It was Muslims who taught the world good manners, forgiveness, and pardon. As for the Christians' claim that they are proponents of peace and tolerance, it is a myth that days will prove false. Virtuous morals are only sought from the lamp of our Prophet (peace be upon him), who was the musk-scented seal of the blessed procession of prophets, and they all followed one religion, which is Islam.