There’s so much wrong with Islam that it can be hard to know where to start.
If you can do anything for your Muslim friend, it would be to love on that person as much as possible.
The main thing you can do when discussing Religion with a Muslim is to stick to the topic of Jesus, pray, and know your Bible.
Muslims ask many sorts of the same questions; ie: “Where did Jesus claim to be God.” I have John 20:28 memorized just for this occasion. I ask why they don’t obey the command of Jesus to “Go therefore into all nations baptizing in the name of the Father, Son, Holy Spirit.”
This will always lead to the accusation of some type of “corruption.” I then usually inquire why the Muslim person asked me where Jesus claimed to be God if they don’t care what the Bible says… But it doesn’t really matter.
After that I show them the love of Jesus found in the Gospels.
A number of good answers in the thread, and yours is a good start, with one exception, which I’ll get to. A loving, charitable approach and prayer x 10 is where to begin, I agree. And, like you said, focus on Jesus Christ.
Years ago I asked the same question you did regarding baptism; don’t recall what it got me, but a good one nonetheless. The reply might have had something about the injeel, if you want to pursue that mystery.
I agree you need to know the Bible; it’s ALWAYS good to know the Bible, period. But many Muslims know their Islamic Bible talking points; they know there are… “weak spots,” for lack of a better word. Skeptics of the divinity of Christ want to know “Where does Jesus say ‘I am God?’ For something that important, it should be that clear,” they say. Or the Trinity. That can be a tough sell with the Bible alone, imo; it’s a complex concept. Catholics have Sacred Tradition in addition to the Bible. Muslims are a real preserved word-of-God scripture bunch with expectations.
But I agree. If he’s not interested in converting, it’s a useless enterprise. A person does better by being an exemplary Christian.
I totally agree, and I should stop right here, but the suggestions being offered can be applied to other people/Muslims, not just this guy.
You can bring up the crucifixion. Even skeptical sources say that Jesus died on a cross (including Bart Ehrman, who muslims love to quote). It’s one of the most certain events in all of history. Muslims believe in things that have less evidence than the crucifixion, so why the inconsistency when dealing with the crucifixion?
Exactly what I was going to say.

And it is key, imo The death and resurrection of Christ is the most fundamental belief among Christians, and Muslims have no answer for it.
Historians (along with Erhman, their favorite “scholar”) overwhelming agree that Jesus existed and was crucified. The Quran simply states it didn’t happen (“they killed him not” ) and offers no details, other than God made it “appear” that Jesus was killed. Nothing beyond that on the death of Jesus, the messiah in Christianity and Islam! An event that God knows (and theoretically Mohammad) will be believed by billions, yet the Quran just glosses over it. Unbelievable.
More unbelievable, is that a loving, caring benevolent God mislead billions of people with some sort of switcheroo or trick. That defies common sense, and it is where Islam falls flat on its face.