The desire to excuse the Muslim's evil ways and to sanitize their devilish teachings is the greatest mystery of our time.
These multiculturalists desperately want Islam to be something it is clearly not. Their mistaken beliefs about Islam suit their anti Judeo-Christian beliefs, so they press on trying to believe the lie. see
"For this reason God will send upon them a deluding influence so that they will believe what is false." 2 Thessalonians 2:11
You also have centered on an undeniable truth. The hatred of the left for Christians is so intense that they will accept the evil of radical Islam before they will accept the grace of Jesus.