Complex sentence: Now the critique against other religions is not rare amongst Buddhists, so, because they see many mistakes, this explains why Kalachakra exists: by it, no controversy is created with others, because the controversy is sidestepped by this incomprehensible form of Kalachakra.
Split into simpler sentences: Now the critique against other religions is not rare amongst Buddhists. So, because they see many mistakes, this explains why Kalachakra is needed: and by it, no controversy is created with others; because the controversy is sidestepped by this incomprehensible form of Kalachakra.