Christianity had a chance, but destroyed it by adopting the Old Testament to justify an authoritarian Church. Many "Christians" simply ignore the New Testament as an inconvenience.

As for the Crusaders, they were a bunch of rabble more interested in looting and fighting each other than in fighting Islam. They were encouraged by the Church, of course. Also the Church's slaughter of the Cathars in southern France over heresy is something that should not be forgiven. "Kill them all, God will know his own".

Religion may be a pretense, but it is a much too convenient pretense, and needs to be brought under control worldwide.

Islam will be perhaps the hardest to bring under control, due to its size, that it has been specifically designed to prevent modernization, and that all Muslims are bound by the religion to kill their friends and neighbors should any stray into "apostasy" (variously defined).