Many people believe in a supreme creator god because they use common sense. Common sense is acquired from our personal experiences of how the world works. Obviously our common sense is thus limited by our experiences - lived or learned. Common sense is good for common, every day life. But is it wise to use common sense to explain uncommon, exotic phenomena?
Theists know that complex machinery and human technology come about by human creators. Using common sense they project this principle of creation of the functional and complex unto the natural world. If a house needs a designer, then surely the universe does too, they reason.
But remember what we said about common sense being informed by human experience. We know from human experience that human technology needs a creator and it's possible to see human technology in the process of being made. What experience do we have of universes being made? None.
Therefore common sense cannot be applied to the question of the origin of the universe. It is simply not a subject that can be adequately addressed with common sense. More than that, it would be wrong - gravely shortsighted - to apply common sense to explain its origin. Why? Because the universe's origin is uncommon, exotic. Theists are not prepared to do this. They appeal to common sense and arrive at the unnecessarily fantastical explanation of god, which does not match scientific data and the experiences in the world we live in - the very teacher of their common sense.
Tackling the origin of the universe has to be tackled free of the biases of common sense. We have to be willing to consider the counter-intuitive. Today, I was introduced to the Banach-Tarski paradox VIA this video. It is well worth the watch:
http://www.youtube.com/watch?v=s86-Z-CbaHA
This is an example of what I call exotic sense. Common sense limits our reasoning ability to our limited human experience. Tackling the origin needs to go outside of our limited human experience - outside of common sense. it involves thinking in terms of infinity and the paradoxes involved. It involves thinking about how something can come from nothing and, as the Banach-Tarski paradox demonstrates - how many things can come from one. This paradox could provide an explanation for how two colliding subatomic particles and result in the creation of an additional number of particles beyond the number involved in the collision.
One of the yet unanswered questions about the origin of the universe is: what triggered the sudden expansion of the singularity that gave birth to our universe? Theist like insert god at this point, as being the only viable explanation for the trigger. But does it really have to be? What if there was some Banach-Tarski-like phenomenon that cause the energy level of the singularity to multiply?
There are a lot of exotic NATURAL mathematical and physical phenomenon yet to be discovered that could posit a natural explanation for the origin of the universe. There is no need to abuse common sense to come up with irrational claims that ultimately have the consequence of contradicting our common experiences. Any explanation for the origin of the universe must account for what we commonly experience and can be measured scientificly. The god explanation does not.