More correctly, nothing, not science and not religion, answers the question "What caused nature?"
OK, maybe you say, "God is outside of nature?" Still I ask, "What caused God?"
So you say, "God is outside of time. Nothing caused God."
And I say, "How'd that happen?"
Science will be lucky if it ever figures out in any real detail how the Big Bang happened. That shouldn't be a big strike against it since everything else is later than that.
And it's not like anybody else knows.