Tim Allen, the famous actor, once said this in an interview:
"My older daughter is an atheist, and I said, well, philosophically there's an irony there too, because atheists don't believe in God. Well, there has to be a God to not believe in."
Some other Christian apologists sometimes present, in essence, this same argument, although they often don't say it so succinctly and in such a distilled manner, and instead try to dress up and masquerade it in a big amount of fancy words and complex arguments.
The distilled version that Tim Allen spouted immediately reveals the main problem with it: The fact that you could use the same argument to argue for the existence of anything. And that includes other non-Christian gods.
"You don't believe in Shiva? Well, there has to be a Shiva to not believe in."
"You don't believe in Allah? Well, there has to be an Allah to not believe in."
"You don't believe in magic unicorns? Well, there have to be magic unicorns to not believe in."
"You don't believe in bigfoot?" Well, there has to be a bigfoot to not believe in."
The funny thing is that Tim Allen clearly said it as if it was a big "gotcha!" moment for his daughter (and for all the atheists watching) that shut her up so effectively that she had no response.
Yeah, sure, whatever you say, Tim.