The second law of thermodynamics requires that the entropy, or disorder, of the universe must increase or at least stay constant with time. This would seem to imply that the universe started out in a greater state of order than it has today, and so must have been designed.
However, this argument holds only for a universe of constant volume. The maximum entropy of any object is that of a black hole of the same volume. In an expanding universe, the maximum allowable entropy of the universe is continually increasing, allowing more and more room for order to form as time goes by. If we extrapolate the big bang back to the earliest definable time, the so-called Planck time (10^-43 second), we find that universe started out in a condition of maximum entropy -- total chaos. The universe had no order at the earliest definable instant. If there was a creator, it had nothing to create.
Note also that one cannot ask, much less answer, "What happened before the big bang?" Since no time earlier than the Planck time can be logically defined, the whole notion of time before the big bang is meaningless.