As a Christian, he isn't going to accept any evidence you provide from the Koran. You would instead need to make an argument from the religious texts that he believes are valid.

To a Christian, the Koran is nothing more than a bunch of made up stories at best. It has no authority or authenticity to Christians.

You would instead need to try to make your case from the Bible. It's a hard case to make since the Bible pretty clearly indicates he is God, though it is always by implication rather than directly claiming "I am God." Rather it says Jesus made statements that, to the people at the time, would imply a claim of Godship. (And in several cases resulted in them trying to kill him for blasphemy. ) At that point it mostly degrades to trying to prove those claims miss attributed.

You are also unlikely to make much progress in convincing him as well. This debate has been going on for centuries with both sides thinking their view is abundantly supported and obvious.

The benefit of interfaith dialog is much more on making sure we understand each others views. Fundamentally you aren't going to convince someone logically one way or the other. You can counter some objections that result from misunderstandings and ensure your views are well and clearly understood, but that isn't going to convince someone to change their beliefs unless a misconception of your beliefs was their main barrier.

(Full disclaimer, I am a Christian answering this from a Christians perspective in the interest of encouraging interfaith dialog. )

The religion comes after the other two. Allah mentions the other two book in Quran. We respect both main prophets of those faiths, Moses (pbuh)/ Jesus (pbuh). Quran is the only book not rewritten (many times) by humans for their own personal gains. Quran is the truly preserved words of Allah (God) for all Mankind. Prophet Muhammad (pbuh) is the last messenger for all mankind in the line of all Prophets sent before him. One of the best things I love, you don’t need to confess your sins or seek forgiveness through another human to God. You can directly ask Allah at any time for forgiveness, as he is the most forgiving and merciful. 🤲🏼