Dervish has an interesting take on the Jollyblogger posts on Hebrews 6 that I highlighted in my last post. She knows a whole lot more about the history of Islam and Muslim theology than anyone I even know, and she presents a historical introduction to various Muslim positions on salvation. Muslim thought on salvation, the losing of it, and the grounds of it as there are in Christianity, and some of these positions are remarkably parallel to some in Christianity.
Her initial point was that this undermines one Christian apologetical argument, an argument that says that Christianity allows for assurance of salvation but Islam doesn't. I think what she says also undermines one common charge against Islam, that it's a works-based religion with no room for God's grace. That's an unfair portrait of Islam, because some Muslim views are somewhat like Reformation Christianity in that respect. On the other hand, I do think what she's saying undermines a common Muslim apologetic. It's commonly asserted by Muslim apologists that Christianity is fragmented and sectarian, while Islam is not. Nothing could be further from the truth. There have been schisms within the larger umbrella of Islam, one very major one, with some of them leading to as much violence as any of the schisms within the larger umbrella of Christianity. There also seems to be as much variation within Islam theologically as there is within Christianity, so the unity argument in favor of Islam is simply historically inaccurate.