Please clarify. Were the Sikhs for instance wrong to raise an army when persecuted? Of course not, self-defense continues to apply even when it is about religion.

What is wrong is to try to force other people to think the same way as you. As much of what we call “fighting about religion” is fighting to gain control over a government so that it can favor one religion and proscribe another that is wrong. We shouldn’t fight to get our religion favored and another proscribed.

And yes Christianity has a tradition of nonviolent martyrdom. That has not traditionally precluded just war, but if it did it is specific to Christianity. Christians are not required to abstain from pork.