At it�s heart, the cosmological argument for God says that anything that begins to exist must have a cause. Used in conjunction with the Big Bang Theory , apologists can rightly argue that our universe at least seems to have a point of origin and therefore a cause. As an atheist, I reject a supernatural creator that did not begin to exist...so, what caused the Big Bang? Well, I don�t know (which is a valid response .) I only know of scientifically informed options. Quantum foam. I can�t explain this better than Lawrence Krauss so I prefer that you come back after reading the book A Universe from Nothing or after watching a relevant lecture . The best layman explanation I can provide is that �nothing� (the absence of conventional matter, energy, space & time) is an unstable state and quantum fluctuations will give rise to something--even the singularity that became our universe. Self-Causation. Violated causality is a logic no-no, however, it is a valid interpretation of quantu...