But both Christianity and Islam are invasive and if Europe didn't get rid of them it would surely devistate the world.That's not nationalism. You seem to be describing world domination. Nationalism cares about unifying a single nation, sure, but then after unification, there still is a tribalistic divide, divide between nations. Nation-scale tribal groups, if you will.
The only way "nationalism" could destroy all tribalism would be if the whole world was united in one nation, but nationalism as a political philosophy is based on the idea that there should be separate sovereign nations.