The scientists try to escape the question by claiming that there was no time before Big Bang, wherefore there's no point in asking what was before it. That's actually the same excuse Augustine had already in the 4th century about a divine creation: God created time when He created the world, so there was no before.
But the old Greeks were aware that something cannot come out of nothing. The Big Bang must have come out of something, which initiated it. We may be stuck in this universe, in the middle of that cosmic explosion, but none of it could happen without something preceding it. In all eternity, some Greeks claimed.
A divine creation has the same problem: If God created the universe, what created Him? If He has existed forever, we still have no clue as to what He is and why He is.
Fundamentally, the question about a world origin, which has been asked in most cultures and eras of the world, is a paradox. It's like when kids ask why, why, why – at some point, there's no answer.
If existence is bound by the fundamental laws of cause and effect, as Aristotle claimed, we are as far from understanding the first cause as he was. Everything that exists must have a cause for its existence, so there's just no beginning.
I think we get stuck in this paradox because we believe in the concept of time, as sort of an entity of its own, a force ticking on from the past to the future. But time is really just a convention we have agreed on. A way of measuring change: Before it was like that, now it's like this. Without change there would be no time. Actually, without change there would be nothing at all.
So, the basic principle of the universe is change. Things move from here to there, things expand and contract, things get hot and then cold, things grow and decay. What happens is the change. The natural laws we have come up with so far are mere measurements of change. We should try to find the law of change.