I'm going to have to move this up the reading queue. Here is an anecdote I'd never heard before from an interview with Robert Spencer in Our Sunday Visitor's TCA:
Christian history is full of saints and martyrs who have made the attempt [to evangelize Muslims]. Most notable, of course, is St. Francis of Assisi, who, during the Fifth Crusade (1218-1221), ventured behind enemy lines and issued this challenge to the Sultan Malek al-Kamil ("Perfect King"): "Light a great fire. Let your priests and mine enter it, and you will see by what happens which of our two religions is the more saintly and true."
When the Sultan told Francis that he didn't think his "priests" would go for that idea, Francis offered to jump in alone. The Sultan declined to take Francis up on his challenge. Impressed by his zeal, however, he gave him safe passage back to the Christian lines.
That story reveals not only the depth of Francis' faith, but the tenacity of Muslims in resisting evangelization...Christian outreach to Muslims has accordingly focused more on charitable works than on open evangelization.