> Isn't that true of Christianity as well?

No, definitely not with the same authority. If you take the Bible as the equivalent of the Quran, and the church fathers as the equivalent of the hadiths, neither has any endorsement of conversion through threats of violence. Jesus was never a political or military leader, nor were the first few generations of Christian leaders.

I cannot give as clear an answer with regard to islam, because I do not know enough in depth, but there are a variety of interpretations. There was persecution of religious minorities in the Muslim empires, but mass slaughter of those who refused to convert would have inspired rebellion. The conversion did happen in places like Egypt and Syria and Persia and there was coercion.

As for Indonesia, the GP did not claim Islam spread only by the sword.