"He declared himself an apatheist instead of an agnostic on Scarborough Country on April 24, 2007."
Before his movie came out.
"I don't know" and "I don't care" are not mutually exclusive ideas. Just because he said "I don't know" doesn't mean that "I don't care" doesn't apply equally or more. I've seen the movie multiple times myself, and I watch his show on HBO. "I don't know what to believe" sounds more like something an agnostic would say. If anything, Bill Maher would say "I don't know and I don't care."