Many of you have probably heard of the multiverse hypothesis, and how it is used by scientists, most often with worldviews of methodological naturalism, to deny that the fine-tuning argument proves God conclusively  (In case you aren't familiar with the fine-tuning argument, here's a quick run-down:https://en.wikipedia.org/wiki/Fine-tuned_Universe).  Their answer for this is to use the newly developed multiverse hypothesis, that's used to explain some particulars of quantum mechanics, particularly the "double-slit experiment" and string theory.  Basically, if there are infinite universes, with infinite possible constants, or lack-thereof, then our universe is just a "random lottery winner" out of the other ones, and that's how we ended up with a universe where all the natural laws, molecular make-up of things, ect. all work together to form things such as planets, stars, life, and other complex things, simply because it's one out of infinite, or many many other universes.

Now, here's where the fun part comes in:  The basic definition of naturalism is: 'the belief that nothing exists outside of the natural world', with a particular disregard to God, spirits, angels, demons, ect. However, the multiverse theory posits that there are other universes that exist outside of our own, in other words, they exist outside of the natural world.  Are you starting to see the problem here?  Basically, if the multiverse theory is false, they have no alternative to God to answer why the universe is as it is, and if it is true, then naturalism is false anyway, because it posits other universes that must exist outside of our own universe, so it proves that something 'does' exist outside of the natural world, and blows the entire thing out of the water.

Does anyone know if this has ever come up, much less any naturalist has responded to it if it has?

Good Post!

Type in debunking mulituniverse on an Internet search and report back.  I'm interested in the question, but don't have enough time at present.

This isn't so much debunking the multiverse hypothesis as it is debunking the notion that it can posit a naturalistic explanation to the fine-tuning argument, mainly because the multiverse itself would not be naturalistic.  I've seen things online arguing against the multiverse, what I haven't seen are things online arguing against the philosophical implications of the multiverse.