update and bump (Oct 13, 1:35 pm) - Thameed has replied in the comments below. Thoughtful stuff; I'll work up a full reply for late tonight. Don't let that slow down anyone else, however.
original post (Oct 11, 1:27 pm) - Stacy of Still Stacy (funny how that works out) had a running discussion with a couple of Muslims commenting at her blog, taking issue with some of her statements on Islam. She offered to give them a post of their own, and one fellow, Thameen, has taken up the offer.
This deserves some in depth discussion, but for now I observe that there is one big thing that Thameed only hints at, and that ought to have been stated plainly for the record. Islam teaches that Jesus was a prophet to the final revelation of Mohammed; as a result, the word of Mohammed is not open to any sort of discussion. (If I'm wrong on this, Thameen, please explain it further.)
In general, Westerners (even non-Christian) deal with Him on different terms - they accept or reject His claims, but in either case, it's a valid topic of discussion. Even the old Christian bumper sticker, "He said it, I believe it, that settles it," has as its fulcrum that key element - I believe it. It has been considered and accepted. And after this, the consequences get a lot of play: because I believe it, how then must I act? How do I reconcile my daily life with the life I am called to live in Him? And if serious new evidence or arguments come around, the question goes back on the table.
Having a similar discussion in Islam is questionable at best. Thameen mentions that "when you move away from the very basics of Islam, it becomes difficult to find consensus among Muslims." He does not mention that the reason why is that nobody opens the debate that may eventually lead to some consensus. It's too risky.
Say what one likes about Christianity - many already have, some of them Christians - but they've never stopped hashing out the details amongst themselves. Much is made of the infighting that has led Protestants, Catholics, and Orthodox to spill blood over those details; but Islam doesn't have that debate across sectarian lines that I've seen, and it hasn't spared them a jot of the bloodshed. Muslims claim more Muslim lives each year than any Western country can lay claim to, and often it's not about disagreements, but agreements: honor killings, for example, are carried out against family members in accord with a point of conduct not kept. (That the victim of the killing never consented to the conduct - or may have had absolutely nothing to do with it at all - doesn't seem to be the point.) The sectarian violence is deplorable, but one culture shows evidence of progressing beyond it, in spite of it; the other doesn't.
When it comes time to interact with other cultures, the West, informed by centuries of dealing with its internal differences, comes out much further ahead - they don't avoid evil, but they have a mechanism that helps to mitigate their misdeeds. Islam, informed by centuries of avoiding uncomfortable self-examination, tends to deal with other cultures in the same vein, and makes many of the same mistakes, but with aggravating factors.
This may seem harsh. I'm trying not to be; I see Thameen's grace and generosity and count it as great progress. It's just an outside observation.