A Post written by Cathoholic Anonymous obtained at Phatmass
What Never to Do
1.) Don't assume that you know more about Islam than the Muslim standing in front of you, just because you've read a Wikipedia article on jihad and have memorised a few Arabic terms that you can barely pronounce. You don't. Respect their knowledge and don't insult their intelligence.
2.) Don't argue about the Qur'an with Muslims. Again, their knowledge of its meaning and interpretation is likely to be far beyond yours - no matter how many pseudo-scholarly Robert Spencer books you've read. If you come out with the tired old "Islam preaches death to the infidel" line, the average Muslim will immediately think, "Here is another one who is trying to make out that I believe things that I don't. Why should I listen?"
3.) Don't make the mistake that Budge's article makes and assume that Islam is an Arab religion or that the majority of Muslims are Arabs. Be sensitive to the culture and nationality of the individual. They will respect you more for it.
4.) Do not drag up honour killings, female genital mutilation, or the death penalty for adultery. The majority of Muslims have no intention of committing a so-called honour killing, mutilating their daughters' genitals, or committing adultery, but nearly all of them will have misconceptions about the Trinity and what it means to profess faith in Jesus' divinity. Talk about stuff that they actually believe and that is actually relevant.
Useful Topics to Discuss
1.) Monotheism. Many Muslims have real difficulty with understanding how Trinitarian faith can be truly monotheistic. In Saudi curious and well-meaning people would quite often ask me, "Why do you worship three gods?" The more knowledgeable would ask, "How can God be three distinct Persons but still have the same essence?" This is a big area of interest and confusion, so make sure that you are knowledgeable. (It is also worth noting that a lot of people who convert away from Christianity do so because of a poor grasp of Trinitarian theology.)
2.) The incarnation. A lot of Muslims have a hard time distinguishing the difference between the theology of the incarnation and outright idolatry. The best place to begin a discussion about Jesus' divinity is with Mary. Muslims have considerable respect for Mary (Marian-related sites in the Holy Land are places of pilgrimage for Muslims too, especially her well at Ein Kerem). There is Qur'anic support for both the Virgin Birth and the Immaculate Conception, so this is an ideal place to begin discussion about Jesus' life.
3.) The crucifixion. The primary Islamic argument given against Jesus' tormet is that God would never allow such a noble prophet to suffer such an agonising death. A different concept of God is at work here. Muslims envisage Him as being exalted, glorious - He would never share in human suffering. Yet the glory of Jesus was the cross. The entire suggestion is revolting to Muslims. This is a delicate topic for that reason and should be approached with sensitivity.
4.) Sin, free will, and the hope of redemption. Muslims are, by and large, believers in double predestination. (Not all of them are, so ask the person you are talking to what s/he thinks about this topic before proceeding.) As in Judaism, 'salvation' is a foreign concept to most Muslims. Forgiveness is not. One of the ninety-nine names of Allah is 'the Great Forgiver'. Talk about the person's image of divine forgiveness. Is there a limit to it? What must a person do to receive mercy? Is it a gift for everyone? Is there any tangible evidence of mercy on earth? (This discussion could lead to the centrality of the crucifixion and resurrection in Christianity.)
1.) Talk with people, not at them. Realise that their spirituality is not all about 'holy wars' and 'honour killings', that they have a genuine love for God, and that you are questioning something that is very precious to them. Be gentle. I've seen a lot of missionaries at work with Muslims, all with the best of intentions and many of them with the subtlety of your average kitchen mallet. They do more harm than good.
2.) Ask questions about the person's understanding of and concerns about Christianity. A lot of Muslims whom I've met are put off by the lack of structured, disciplined prayer that they see in Christianity. They are very attached to their five daily prayers and regular remembrance of God. (This is where the Divine Office comes in very useful.) Others may be worried by the lack of modesty that they see in the dress of Christians. Still others are concerned that they will be expected to start aggressively condemning their Muslim family and cut off all ties with their friends. The concerns vary from person to person. Listen and understand.