As I understand it, Muslims in Iraq are now converting in record numbers to Zoroastrianism and Christianity. ISIS is, as it turns out, very bad advertisement for Muhammad. It is not unreasonable to speculate that there will be a Christian state in the Middle East when this has all come to pass.
I do find it rather interesting how modern Christians living so comfortably in the West (for now), chide these men for their self-defense. Christians have invariably been armed throughout the centuries.