In The Crucible, why can religion cause conflict?

History tells us "religion" or faith is the cause of most wars and conflicts around the globe; that's still true, at least to some extent, today.  It seems to me the reason religion can cause such conflict is that every faith thinks it's right and must convert or eradicate others in order to fulfill the mission of that faith.

It's ironic that a religion of love and acceptance can create war and hate; however, true believers (plus the fanatic fringe of any faith) are motivated to win or convert others at any cost.  Those who are not members of that faith can then become the "enemy." 

When people are willing to die for a cause, unfortunately they're often willing to kill for that same cause.  In The Crucible, the belief that witchcraft was a sign Satan's presence in their town caused them, in their religious fervor (and other motivations, as we know), to eradicate or "kill" any signs of this enemy of Christ.