It is amazing that Christian "apologetics" are taking this tack; it seems they can no longer provide good reasons why people should become Christians, instead they are attacking other faiths.
Robert Morey - the source of this "Moon God" crap - is angry with lots of folks. In addition to Muslims, this bigot has written vile screeds against Mormons, Jehovah's Witnesses, Wiccans, Free Masons, and just about everyone else who does not adhere to his constipated world view. I'll bet this tight-ass hates Halloween, too.
As you point out, Christians who attack the historical roots of other religions are playing with fire.