If we define extreme religions that are really unacceptable, and keep practices that are really against the general belief, and we can even describe the practices as crimes, why can't the government outlaw the extreme religions. As the role of the government is to protect the safety of citizens and civilians, there is definitely a need to outlaw extreme origins.
"Outlaw Extreme Religions" would be a very very dangerous measure. For instance, many religions have committed barbaric acts at some point in their history. For instance, up until about 200 or 300 years ago Christianity was a violent religion. Even though Christian terrorism is very violent today, somebody could still count it as a violent religion. Islam is a violent religion today, but should the peaceful Muslims be banned from practicing their religion because of the violent ones?
Who ultimately decides what religion is peaceful and what religion is dangerous? This question should be rephrased as "Should we outlaw Extreme Religious Acts?" Then the answer would be yes.
When people commit crime, we should outlaw it but we should outlaw belief in it or the freedom of expression to practice it. You can't stop people believing in something unless you convince them of otherwise and to outlaw the freedom to express the practice of that religion would violate human rights (the UDHR).
No, because whether a religion is extreme or not is subjective. My sister-in-law thinks Calvinism is extreme, but Calvinism was pretty normal to the Puritans. Now, there may be religions that sacrifice cats or humans, but I think what should be outlawed is human and cat sacrifices, not the religions that practice them. If it happens that outlawing human and cat sacrifices prevents people from practicing their religions, then so be it, but I don't think law should target a religion explicitly.