There’s much of it in the comments below – I’ll just pull this, from long-time reader and wise commentor Julia in this thread:

Note the circumstances of the Byzantine Emperor’s remarks. He is at his military camp outside Constantinople – his capital city is under seige by Turkish Muslims. He is trying to have a civilized rational discussion with a Muslim (one of the enemy) about the very thing that is threatening his 1000+ yr empire and capital. Perhaps he was trying to find some way that the two religions could live in real peace.

I wish we could read the rest of the conversation in that book. I wonder if in modern lingo the Emperor is trying to say: Why are you attacking us and saying that God approves of this violence? Isn’t that what all of us in the US are wondering today since 9/11?

I.E. Explain yourself: why the heck are you attacking us and saying that your God wants you to do it to spread his faith?

Benedict wants the Muslim world to think about that and give us a thought-out answer so that we can enter a dialogue about our differences based on reason. If the Muslim world can’t do that, then how the heck can we make real "peace" and avoid all-out clash of civilizations?

Exactly. Thanks once again, Julia.