> Historically, as Christianity spread around the world over the two millenia, it would often adapt and absorb indigenous beliefs and practices of converted pop

> Historically, as Christianity spread around the world over the two millenia, it would often adapt and absorb indigenous beliefs and practices of converted populations Certainly, in the Eastern Orthodox church it's commonly called "baptizing the culture". The idea was/is to take what is good from a culture and to incorporate it to help people become Christians. Also it's a core part of Christian missionaries to learn the language and translate the scripture, and if needed to create a written form of the language. So I'd agree Christianity has always been a bit of a symbiosis of cultures, analogous as you said to endosymbiosis. It started purely Judaic, incorporated large parts of hellenism, and spread globally and imported more bits. The Jewish and Hellenic pieces aren't completely mixed, sort of similar to a mitochondria actually. Then again it makes sense of a religion with a core belief that God became man and created a symbiosis of the two as their savior.