Because radical Islamists attack Christians and Jews equally. Actually they attack everyone that isn't a radical Islamist, including an awful lot of Muslims. In fact the vast majority of the victims of Islamist violence are other Muslims.

It's important to note that we throw around terms like The Muslims as though all Muslims and Christians, etc have the same beliefs and agenda, and that's clearly not the case.

Today's mainstream religion is something entirely different from yesteryear. I'm a Muslim, who has good friends who have faith in any and almost every religion (excl. extremists).

The subject is completely invisible to us except when we discuss interesting parts of the religions we believe.

I for one believe that religion is an ethics and conscience system, and when practiced correctly, all of them points to the same direction, albeit with different narratives and paths.

> when you add in Islam, why do Christians and Jews suddenly become political allies?

Goes back to the Crusades, the Islamic invasion of Europe and the fall of Constantinople

It’s not like Christianity embraced Jews either, but they did not present an existential threat