Scientists have discovered that there are certain constants found in the laws of physics that need to be set very precisely in order for life to exist in our universe. The best explanation for these facts is that our universe was designed by God. However, a lot of atheists reject this conclusion by arguing that our universe is just one of a very large number of universes (perhaps an infinite number) and therefore the fine-tuning can be explained by chance. The problem with this is that it means some very "absurd" universes can exist out there. And if these universes can exist then it's possible one of those "absurd" universes is actually the one we are in but we just don't realize it.
This quote from a Babylon Bee article is satire but it helps illustrate the point.
[An atheist named] Hemsworth stated that in the past he had used the argument of the “Flying Spaghetti Monster” in debates with Christians to point out the absurdity of their beliefs—but once he discovered the multiverse theory he realized that he, too, believes in a universe that is ruled, governed and possibly even redeemed by a flying monster made of sentient spaghetti. “I have to accept that every possible universe might exist without exception—except, of course, the one described in the Bible—even if that means I accept the Flying Spaghetti Monster as my lord and savior,” Hemsworth said.
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Reference
“Atheist Accepts Multiverse Theory Of Every Possible Universe Except Biblical One,” The Babylon Bee, February 9, 2017, https://babylonbee.com/news/atheist-accepts-multiverse-theory-every-possible-universe-except-biblical-one.