For many atheists, a major stumbling block is the belief – the insistence – that this universe is “all there is.” Considering the likelihood of God’s existence from this starting point will often cause the atheist to engage in circular thinking, as evident in a recent challenge posted on this site:
“For gods to be gods they have to be supernatural - agreed? For something to be supernatural it has to exist outside of the universe - agree? Since the universe IS everything, there is nothing outside, there is no 'outside.’ Therefore nothing can be supernatural, which means that any being demonstrating the traits of a god is nothing more than a powerful evolved creature that lives in the same universe as we do, therefore is not a god and not deserving of worship.
I'm on solid ground when I say no gods exist. Disagree? Prove they do.”
With just a bit of reflection, it is apparent that the skeptic has built his conclusion right into his premises. By defining the "universe' to be "everything," and “supernatural” as being "outside the universe," the only possible conclusion is that there is no God. Restating the syllogism, the challenger is saying: To exist, a being must be within the universe. By definition, God is that being which is outside the universe. Therefore, God cannot exist.
The problem with the conclusion is not the logic employed but the accuracy of the premises involved. Why should we assume that the universe is everything, that there is nothing outside of it? The challenger presents no evidence to support his claim, nor does he provide an argument. He simply assumes that the universe is all that there is. This is very shaky ground upon which to build a belief system.
When a Christian refers to the "universe" - at least an "old earth" believer - he is usually referring to the thing that popped into existence from "nothing" some 14 billion years ago. It consists of length, width, depth and time. Perhaps in the first fraction of a second, it also consisted of additional dimensions. There was a before to the universe and there will be an after; otherwise the universe itself would be infinite and eternal, which science tells us it is not. But if time as we know it began with the Big Bang, then this before and after exist in a way in which our minds cannot fully comprehend.
Since a "something" cannot come from a "nothing," this universe needs a source adequate to explain its presence. The source must be immensely powerful, given the size and grandeur of what we see, and immensely intelligent, given the precise mathematical order built into the laws of nature. This source must be artistic, for the universe contains much beauty. But the source, while capable of entering this universe, must exist outside and apart from it; otherwise it would be part of the universe and in need of explanation.
This challenge is not unlike a skeptic who examines a house he comes across. He sees that it is built to precise specifications, that it is functional and that its appearance demonstrates a symmetric elegance. Because he was not present when it was built, and because the present owners acknowledge that they did not build it, he concludes that it must always have existed, that there were no architects, no carpenters, no plumbers.
No rational person would draw such a conclusion, because the existence of precisely built things requires a builder. But, in holding his view, the atheist has abandoned rationality in order to arrive at the place he began.