Comment by thinkingemote

The separation of church and state in the US was for the state to stay out of religion.

(the US was founded by religious exiles from a state which didn't stay out)

Religions are explicitly political but politics shouldn't interfere with religions. To follow your religion means interacting with the outside world. It's not some personally private thing like a harmless badge you wear (although there are American faith communities that advocate for that).

The cases in the past where political have interfered with religions are often, ironically enough, by other religious politicians. Hence the good idea to separate church and state.