Islam is fine, but it's presented as an "As is" religion like Christianity. It's not. If you practice Islam like a practical, logical based religion, you will end up with what we have, millions of people trying to kill and murder, wipe out cities, villages and towns full of people who have done nothing wrong. 

Sufism is the number three denomination of Islam. . .Sunni is by far the largest sect, with 70-80 percent of the religion, and makes up the majority of what Muslims practice. Shiite is supposedly worse, but they have the same thing in common with Sunnism.

Christianity is based on the perspective that "Here's knowledge, take it and have faith in who gave it to you." 

Suffism is like "Decipher of the meaning of this heavenly hieroglyphic and discern what it means" Or at least something like that.