How can you lack belief in the existence of god.
Simple - "X believes in god" is a statement/predicate about human X.
For a non-believer, the state of believing in god is exactly as incomprehensible as the state of not believing in god would be for a believer. Both need mind-shattering experiences to truly switch around, there is no way through simple logic to change that (proof: if there were a way - in either direction - the issue would be resolved by now, and we would not be having this discussion).
Even indoctrinating gullible young humans for many years through childhood and adolescence does not with certainty work to instill either belief or disbelief in them, as demonstrated frequently by young adults switching to the "other camp" when out of the control of their parents or community.
God here I defined as prime cause. As the world is a sum of collections of events, causally linked to the past through time, then there must be a prime cause.
There are several (simple, logical) fallacies in those sentences:
- "God is a prime cause" is a definition, and has no "true or false" meaning; at this point in your argument it gives an attribute/predicate ("is a prime cause") to a concept ("god"). That is certainly applicable for mono-religions because humans simply created that definition. But from this definition there does not follow "Every prime cause must be god".
- If, at this point in your argument, you imply "God is" (that is, "God exists"), then you can stop right there - then you will have started the argument with the fact you wanted to prove, in the first place.
- "[All events are] causally linked to the past through time" - that is false. All spacetime points/events which are outside of each others light cone are not causally linked. And this predicate of not-being-causally-linked survives back right up to the instant of the Big Bang.
- "there must be a prime cause". No. There may, or may not be a prime cause, but "must" is patently false here. We can easily think of ways that the universe could start without a prime cause. It could be an infinitely repeating meta-process of universes being separated by infinitely many Big Bangs. It could be that the concept of "cause" itself breaks down at the singularity. It could be that the next Hawking resolves the error in our formulas and the singularity simply disappears. It could be that our universe sprang into being spontaneously the same way we know/assume that certain virtual (but still real) quantum particles spontaneously appear and disappear even in the deepest vacuum, with no single other particle anywhere around. Plenty of possibilities, none of which anyone can disprove just yet.
- You did not write it, but there is an invisible statement at the end of your argument: "Therefore, god is that prime cause". This is not the case either. You can define God to be a prime cause, but you cannot define it to be the only prime cause. Hence, even if there were a prime cause (which I am not arguing against!), nothing tells us that that must have been god.
As of now big bang singularity has been discovered.
No. The Big Bang has not been "discovered", almost all of it is just one theory on top of another on top of another. The only thing that is certain is that we have not witnessed anything that disproves the Big Bang. That is the nature of science. Until we disprove the Big Bang, it is a possibility. We can get ever more sure about it, but we will never know with absolute certainty.
Every scientist underwrites that contract. The scientific method is about "formulation, testing, and modification of hypotheses". We can, by principle, never "prove" the Big Bang, we can only disprove it by witnessing something that conflicts clearly with it. Science has rewritten itself over and over again. Being 100% irrevocably sure of something is a clear sign of pseudo-science or religion.
Specifically, while we are pretty sure that "something happened" back then, we also know perfectly well that our current mathematical model of the Big Bang is wrong (or at least incomplete). Not wrong in the sense of "false", but wrong in the sense that we need a much more complicated theory. Similarly to how Newtons laws are not quite false in everyday cases, but are patently wrong in the big picture. We are still thinking about it...
But to say this big bang to occur in nothingness, where there is no volume, no time, no energy, completely nothing.
To say that would be extremely false. The opposite was true. From the Brief Answers to Cosmic Questions, by Harvard University:
``No. The Big Bang was not an explosion IN space. It was a process that involved ALL of space. This misconception causes more confusion than any other in cosmology. Unfortunately, many students, teachers, and scientists(!) mistakenly picture the "Big Bang" as an explosion that took place at some location in space, hurtling matter outward.
In reality, ALL of space was filled with energy right from the beginning. There was no center to the expansion, and no magical point from which matter hurtled outward. The confusion arises in part because of the amazing conclusion that the OBSERVABLE portion of the universe was once packed into an incredibly tiny volume. But that primordial pellet of matter and energy was NOT surrounded by empty space... it was surrounded by more matter and energy (which today is beyond the region we can observe.) In fact, if the whole universe is infinitely large now, then it was always infinite, including during the Big Bang as well.
To put it another way, the current evidence indicates only that the early universe - the WHOLE universe - was extremely DENSE - but not necessarily extremely small. Thus the Big Bang took place everywhere in space, not at a particular point in space.´´
On to your argument:
There ought to be cause(s) to this singularity,
Maybe there ought, maybe there ought'nt. We certainly do not know enough about the universe to know. Maybe the physical, real phenomenon that is represented by our mathematical singularity is precisely something that precludes any causality (insofar as causality is a "physical" thing in the first place, and not just a mental crutch we need in our limited understanding of reality, the answer to which I'm pretty sure nobody knows with certainty).
But even if it is that way, then...
In the end it still lead to god.
... that last argument is again a fallacy. You start out by proposing that everything is caused by god, and therefore everything leads back to god. Logic does not work that way. In the best case (if there is a real god which functions the way you propose), you can just skip everything in your argument, and be done with your first assertion. And if there is not, then you are starting from a false statement, from which you can, by logic, prove anything. Hence, this argument proves nothing.
Be sure to understand that I am not telling you that it needs logic for god to exist. But for some people, including scientists and philosophers, you do need logic to convince them of something... hence, to go full circle to your first question:
How can you lack belief in the existence of god.
Simple - nobody has found a logical, irrefutable proof that works without the assumption of the existence of god, yet. Hence, some people, who require such, do express a lack of belief.
