It is often derisively claimed that 'atheists' believe that something came from nothing (despite the fact that "creatio ex nihilo" has been Catholic dogma for centuries).
Of course this is utterly ridiculous because what atheists actually believe is that theists have not met a reasonable burden of proof for their claims -- atheism itself doesn't proclaim to KNOW anything about the origin of the universe.
But as I see it, There are only two options that have been put forth:
(1) In the beginning there was absolutely and truly nothing, not the vacuum of space, not time, and NOT god but truly NOTHING. And then out of this absolute NOTHINGNESS sprang the SOMETHING that now constitutes ultimate reality. This SOMETHING may be our universe or it could even be a precursor that existed for mere moments or even unimaginably vast amounts of 'time' before our current universe.
(2) There was NO beginning. Whatever "is" is, is eternal (take that Bill Clinton). And by that I mean that ultimate reality must be SOMETHING and that something would have to be eternal. That SOMETHING may or may not be our spacetime.
Neither option can really be said to be 'more likely' since we have absolutely no frame of reference from which to judge such things. We can go on our own intuition but even extremely well-educated and intelligent individuals could disagree.
I am actually partial to (2) despite constant assertions by theists that atheists "must" believe that something came from nothing. In my view of (2), Universes sometimes spring quantumly from the eternal void (in a similar fashion to virtual particles) with a relatively infrequent intensity that unleashes something along the lines of the proposed quintessence ( http://en.wikipedia.org/wiki/Quintessence_(physics) ) which causes a rapid, inflationary period in the early burst of energy that prevents the normal quantum collapse. [note that the void in this case is NOT the vacuum of space]
In this model our universe sprung from the void as an energetic fluctuation so violent it created its own spacetime. The remainder of the energy twisted into nanoscopic vortices which have continued to whirl for billions of years, twisting into ever heavier particles through gravitationally powered fusion and then exploding again and again until enough of their energy was spent that the earth could form out of the fiery violence and then cool to the point where organic chemistry could continue the dance at an ever finer pace, with ever more detail until, in a sense, we have crystallized out of the substance of the universe.
I see no need in all of this for a personal, theistic god, who bothers to answer poorly conceived, ignorantly vile, and conflicting prayers; who watches us pathetic humans with a critical eye jotting down every time someone masturbates for later retribution on their 'soul'; who creates us with a flaw, damns us for having it, and nearly destroys us. And then for a small band of relatively ignorant humans to claim that THEY know the mind of this god and THEY know this gods Will and Wishes, and that they are now his authority on earth over all others... And then, to ice the cake, after many claimed millennia of this god being AT THEIR SIDE (winning battles, slaughtering first-born, Engineering great vessels, flooding the entire Earth with an unimaginable quantity of water which then disappears, turning water into wine (I thought yeast did that), we're supposed to believe that just because we have scientific methods now that this god has gotten shy and gone completely undetectable?
I believe that we are responsible for our own actions and that we are held accountable to our human morals by society. There are 'right' and 'wrong' actions for humans but these moral concepts are creations of human brains and derive from our ability to formulate fairly accurate predictions of behaviors and consequences for actions.
If it were absolutely wrong to murder then it would have been WRONG for god to command Abraham to murder Isaac. And yes, I know god cheated in the end but it was STILL WRONG for god to have commanded it and it's wrong for people to consider this a work of any moral authority when it repeatedly commands murder, genocide, infanticide, genital mutilation, rape, and many other horrors and NEGLECTS to mention anything about things such as microbes.
But in the process of evolution humans have acquired a sense of empathy and compassion because having those allowed us to operate more effectively as a social group which has allowed us to survive. And we have, therefore, collectively agreed that murder is not one of the things we want to tolerate. And thankfully we have moved past the more ignorant "morality" of the bible. For example, we no longer force a virgin to marry her rapist or force him to pay a bride price to the father. Those things were NEVER moral, NEVER acceptable, and NEVER divinely commanded. They were the unfortunate laws of the time. Thank GOODness we have moved past them.
Human morality is constantly shifting, and changing, and adapting to the situation.
3000 years ago murdering other humans en masse was justified in THEIR minds. They were, in a sense, protecting their own. It wasn't morally right by todays standards but THEY didn't have much of a problem with it (although I'm sure the hundreds of thousands of people who were murdered probably objected). They also had little or no compunction against enslaving their enemies. Or beating them, sometimes to death.
And then things got really twisted up in their minds. They decided that, with their 'newly' found moral senses, they would make laws. Laws like, if your child is disobedient you can stone them to death. Laws like, women should be silent and subservient to men. Laws like, how much you can charge when you sell your daughter into sexual slavery. And Laws about taking slaves from your conquests. By ANY modern standard, these are immoral and primitive codes. EVERY modern Christian (sect) cherry picks through the Old Testament books and decided, based on nothing more than their own innate, modern sense of right and wrong, which of those codes they will decide still apply and of those which they still accept they redefine the appropriate punishments for them (very few modern Christian sects still hold to stoning people to death although they DO still exist).
And a few Islamic cultures (and other religions as well) also still practice stoning to death. They consider these actions moral, not just moral by human standards, but ORDERED by god and thus RIGHT by definition that CANNOT be questioned. Anyone who dares to question this authority is also Stoned to Death of course.
And even if modern Christians do not generally stone people to death they still follow this same kind of ignorant logic to equally ignorant conclusions about what is morally right because THEY believe it is ordered to be so by their "god" (because it is written in a book, written from 3500-1800 years ago approximately). And they ironically consider Themselves persecuted when challenged or asked to justify these beliefs.
Don't get me wrong, certainly not ALL christians nor ALL muslims are bad people (not even most of them) but they ALL support systems that are corrupted, violent, and by modern standards, evil. They also teach falsehoods, that even they don't claim to know directly or have ANY direct proof, as the truth. It IS folly and it SHOULD be unacceptable in this day and age.
If you really must believe in some kind of nebulous supreme power that is just fine with me. Be Deistic (god exists and created everything but is letting things run their course and has no influence over us and doesn't judge us) or Pantheistic (god is essentially everything, god is the universe and the laws of physics) or whatever floats your boat.
But PLEASE stop trying to claim any kind of personal and direct authority over others on the basis that you claim to know what this being might want from us.