Christian conservative Bryan Fischer on Wednesday claimed that in endorsing marriage equality President Barack Obama was declaring that he's no longer a Christian.

In his new book Believer: My Forty Years in Politics, former White House adviser David Axelrod claims that Obama has been in favor of same-sex marriage for as long as he's known him and that he concealed his support in 2008 for political reasons.

Obama denied the claim, saying that Axelrod has “mixed up” some of the facts.

“I think David is mixing up my personal feelings with my position on the issue,” Obama told BuzzFeed News. “I always felt that same-sex couples should be able to enjoy the same rights, legally, as anybody else, and so it was frustrating to me not to, I think, be able to square that with what were a whole bunch of religious sensitivities out there.”

Fisher explained to his radio listeners that the president's support for marriage equality was a declaration that he was no longer a Christian.

“Think about this for a second,” Fischer said. “President Obama said several times, 'The reason I believe that marriage is a union of one man and one woman is because I am a Christian.' So what does it mean, what are the implications when President Obama says, 'I no longer believe that marriage is a union of one man and one woman?' The implication is, 'I'm no longer a Christian. Christianity teaches marriage is a union of one man and one woman, I used to be one of those, I used to be a Christian, I used to believe in a Christian view of marriage. I don't any longer.' … If you press what Obama's saying there, he would be saying 'look, I'm no longer a Christian.'”

(Related: Obama: Federal law trumps state law in Alabama gay marriage dispute.)