The idea that everything that exists stands in an infinite chain without anything outside as the ultimate cause is an interesting idea but I think it calls for some evidence if we are to accept it. It’s the sort of “extraordinary claim” that some sceptics are fond of demanding “extraordinary evidence” in order to believe.
The atheist position is actually quite a demanding propositIon when you really think about it. Describing it as the fallback position or null hypothesis is a rhetorical strategy disguised as science. Why shouldn’t God as a hypothesis be the starting position? “Because I say so” seems to be the best atheists can come up with.