The atheist's response can range from a rundown on the discoveries of physics followed by some hypothesizing off of what further possibilities are implied by our current body of knowledge, especially through playing around with the mathematics of established knowledge and observed structures and patterns. But the alternative ranges from saying that we don't know. yet, and we are still gathering more data on that front, to that it doesn't matter since it does nothing to hurt our position or bolster any competing opinions, since the religious alternatives are all unsupported by any evidence or observations, and either conflict with existing known scientific principles, in which case there is never an attempt made to justify these impossibilities as being acceptable, or they offer explanations that are at most on par with anything the atheist can offer. Maybe the universe came from the collapse of a previous one, maybe the universe always existed, maybe the universe is a simulation made by beings who are mortal, flawed, and powerless in their universe, just as we are in our own, all of these are superior to the deist proposal of a mind without a brain, possessed of the power to affect the universe through magic. Far superior to the Christian proposal of a God that lives in waters of a cosmic sea, divided from us by a solid firmament that rests over the earth, in which there are windows through which God allows water to pass in order to produce rain on a planet that is possessed of four corners. A God which created this Earth in six days, including all animals, fully formed, built a garden on the planet surface where a man made from dirt named all the creatures, which we are barred from entering due to an angel who guards the entrance with a flaming sword. The Bible is full of statements that aren't so, all of these are justified as being wordplay, but maybe then, the god of the bible is also wordplay, and the whole book is one where there is no god, or heaven, or angels, or souls, and it's all just a book of poetry and symbolism wrapped around a historical narrative that was also proven to be false by archeological findings. Is there a reason that one thing which we can verify to be false is not true, despite it having impact of the narrative, and another thing, less subject to verification, would not? Basically, we have ideas that may be wrong, but we accept that they may be wrong, you offer ideas that are provably false, and you either have no basis to assert them, or you retreat from the really wacky stuff that you cant justify without contradicting observable reality with "it's just poetry bro". Your best scientist was Michael Behe, and he folded like a lawn chair in the only time he was made to take the stand on his knowledge, he was a liar who made money by telling you what you wanted to hear, kent hovind and ken ham were another of your best men in the science field who made fools of themselves the moment they had to converse with someone who knew anything about science or the bible and was willing to challenge them.