1) Scientists are able to accurately model the behavior of reality from the tiniest subatomic scale all the way up to the scale of the entire visible Cosmos, without ever
once having to incorporate a variable into their equations to account for the presence and/or action of
any Invisible Magic Person. Not just gods; this applies equally well to angels, demons, faeries, sprites, djinn, ghosts, devas, bardos, Bodhisattvas, whatever sort of IMP you'd care to name. Any IMP that exists has to make a permanent practice of making itself
more difficult to detect than a faster-than-light neutrino.
[1]2) Most believers, including Craig, already know they live in the same godless Universe we do. They've already got theological rationalizations for why Universe behaves exactly as it would if atheism was true, ready in their back pockets. Imagine if Christopher Hitchens had said, "Oh, we don't have to
debate this at all, we can actually find out!" *snaps fingers* *assistants enter the room, carrying two plates, each with a raw steak, and set them up on stage on little tables* "According to 1 Kings 18:16-45, it is possible to arrange a public demonstration that will show whether Yahweh is the true God, or if he is no match for science and technology as represented by this flamethrower." *assistants hand Hitchens a flamethrower* "So, just like Elijah did in the Bible, I invite you to pray to your god to ignite your steak, and I'll use my flamethrower to ignite mine. We'll see which is real."
Hitchens would not even get through citing the chapter and verse before Craig's mind would start filling with argumentation and explanations for why Yahweh would not answer his prayer as he supposedly did for Elijah. How could this be? How could Craig
know, in advance of performing the test, that Yahweh would not send fire down from Heaven? Even if he thinks Yahweh might not be inclined to, Yahweh is still (supposedly) a being of free will, and there should be a non-trivial chance that he would decide to surprise everyone. This advance knowledge that Yahweh does nothing and cannot be detected (even as a passive object, like a rock),
in principle, extends to any conceivable test anyone could ever think up. Studies of prayer, accident and disease statistics for devout believers, etc.--all will show no evidence of Yahweh's existence and action,
and the believer knows it. Or to put it another way: when it comes to anticipating how reality will actually behave, most believers anticipate that it will behave like a godless Universe. Even the ones who are crazy enough to bet their child's life on their preferred deity's healing powers
still already have an explanation handy if their child dies. We do not see these people saying, "Oops. I guess that falsifies my faith then."
Nutshell: Even believers know we live in a godless Universe. They don't believe in
god[2] they believe
in belief in god. Belief-in-god makes you a good person, provides meaning and purpose to life, makes you a part of the believing community, etc.. To trick yourself into believing that you have belief-in-god, you have to make the claim that you think your god exists, while surrounding that claim with a bodyguard of explanations for why reality behaves
exactly the way it would if your god doesn't exist, while maintaining constant vigilance to never hold both of those thoughts in your head at the same time.
3) Everything we know about Universe militates against the idea that it was purpose-built as a human-habitat. Any religion professing that it was is therefore falsified by overwhelming, literally
astronomical amounts of evidence.