Diagoras,
One of the best explanations for the lack of belief [and belief] in God is the crucial element which is: Socio-cultural environment. There are several levels that contribute to a persons "lack of faith"
1) The individual grew up in a non-religious/non-spiritual household
2) The individual lives in a secular and/non-religious environment e.g. neighborhood, school and community are not religious.
3) The individual grows up ignorant of religion thus develops a natural ignorance [or disbelief] in a spiritual reality.
4) The individual experiences a tragedy in one's life therefore holds religions whose gods are based on universal morality, in contempt.
5) The individual is taught not to believe in God(s)
Diagoras I'm sure of the above five, you are one of the several categories I've just listed. I have spoken with many atheist and actually had a recent conversation with one the other day who called himself, "areligious" meaning he has not particular preference in his dislike for religions and their gods. What I was trying to prove was that the basis of faith [or the lack thereof] are subjective truths only relevant to us. The most important thing I'm trying to say is that whether you believe or not depends upon the environment you grew up in where is may or may not foster your belief in a higher power(s).
Atheist like theist act like what they believe is so object that it can be infallible which is not the case. Although I'm a firm believer in God, I'm not ignorant in the fact that I may be wrong. Because I'm only a human being and cannot possibly know beyond my own capacity I therefore can only say that faith is the backbone of my belief in God and I cannot presume to objectively show that God physically exists. Diagoras no Muslim, Jew, Sikh, Hindu or whatever can show you God. Those of us who believe in God hold God to be incorporeal, that is, a non-material entity. "The molecules in your occular lens" will not be able to comprehend God because physical quality is substantially dependent upon other things and God is without dependencies-so to speak. These are all general beliefs Muslims have of God.
The more important thing to remember here is like yourself, we have grounded beliefs but all of our beliefs are the product of our environment. Diagoras that is why you do not believe in God. But because I grew up in a religious environment, the transition from one Abrahamic faith to another was not difficult because the belief in a higher source was always there.