Denzel said this in a GQ magazine
GQ:How did you feel about Obama endorsing same-sex marriage?
Denzel:What did he say about it?
GQ:He said he was in favor of it. That he didn't oppose it.
Denzel:What does that mean? [laughs]
GQ:It's the political way of saying, "I support it."
Denzel:You know, I think people have the right to believe what they want to believe. And people have the right to disagree with it.