Franklin Graham, a leading evangelical figure, said Thursday that legalizing gay marriage would be a “great mistake” for the United States.

Appearing on CNN's Piers Morgan Tonight, Graham, the son of evangelist Billy Graham, told host Piers Morgan that “God defined marriage.”

“You have to go back to, 'What does God say?'” Graham said. “And it's not what I say at all. It's what God says, Piers. God is the one who defined marriage, not government, but it's God. And it's between one man and one woman. And so to come and try to redefine what God has ordained, what God has blessed, and what God has given would be a great mistake for our government and a great mistake for this nation.”

Graham, who heads the international Christian relief organization Samaritan's Purse, dismissed the comparison to interracial marriages, which were once also banned.

“Aren't we in the same position here?” Morgan asked.

“I don't think, no not at all,” Graham answered. “Marriage is defined as between a man and a woman. And, of course, during the race issues it was could a black man and a white woman, or vice versa, could they get married and that was a debate that we had and they decided yes. But still that is a marriage between a man and a woman, and not two men and not two women.” (The video is embedded on this page. Visit our video library for more videos.)