It’s a little too pat say that Christians and Muslims “understand God differently.” Well, of course they do, but there’s a huge difference between not having enough information–ignorance, basically–and flat-out rejecting the information that’s available. Christians and Muslims, if they are faithful to their sacred writings, don’t just “understand God differently.” They reject the fundamental truths about God that the other religion asserts. This is not at its root a problem of understanding, but of disagreement.
And it’s not wrong to say this. If we truly desire to respect the other person, we need to take his beliefs seriously and not try to gloss over them or shoehorn them into our categories. I think it’s fair to say he isn’t doing that for us–nor should he.