I can think of two opposing views of religious fundamentalists:

1) People from liberal religions should always speak against fundamentalist views. If they condemn others, claim others to be evil, etc. we should not let this view go unopposed.

2) Liberal religions should also be liberal to fundamentalists. To oppose or condemn their beliefs is illiberal even if they are condemning others, accusing them of being evil, etc.

What is the best attitude to have, or can we mix both according to circumstance?