To postualte a god to explain the mere existence of the universe (incl. life, afterlife, meaning, etc.) is in essence the ages old "proof" made by Thomas von Aquin. I.e. "everything must have a reason; to avoid infinte regress, we need a first reason; this first reason is God".
This reasoning actually leads directly to atheism, here's how:
1. Let's accept the presumption that erverthing really needs a reason, a beginning, an explanation.
2. This reasoning does not lead directly to a particular god or religion. It simply leads to some undefined, super-natural cause of the universe, which one may call God, or Allah, or Odin, or cosmological principle, or a bazillion other things.
3. So it leaves you with "there must be something, but I don't know exactly what". Welcome to the agnostic worldview.
4. The comes the question, whether such a cause is really necessary to explain the universe. Knowing at least a bit about cosmology and quantum physics, and having a materialistic rather than a mystical base tendency to explain stuff for myself, I came to the conclusion, that the universe by itself is cause enough to exist.
Basically that is how I came to atheism, esp. step #2 was heavily influenced by the fact that there is a plethora of religions all claiming to hold the one and only absolute truth