Franklin Graham, who is the son of the late evangelist Billy Graham and a prominent supporter of President Trump, slammed Democratic presidential candidate Pete Buttigieg for being gay, Christian and married. In a series of three tweets Wednesday, he assailed Buttigieg for remarks he has made about being a gay Christian.

"Presidential candidate & South Bend Mayor @PeteButtigieg is right—God doesn't have a political party," Graham wrote. "But God does have commandments, laws & standards He gives us to live by. God doesn't change. His Word is the same yesterday, today & forever."

Then, Graham added, "Mayor Buttigieg says he's a gay Christian. As a Christian I believe the Bible which defines homosexuality as sin, something to be repentant of, not something to be flaunted, praised or politicized. The Bible says marriage is between a man & a woman—not two men, not two women."

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Graham, who heads the Billy Graham Evangelistic Association and the Christian relief group Samaritan's Purse, faced a storm of criticism for the comment. Several expressed outrage over the judgment he pronounced on Buttigieg, in light of his support of Mr. Trump. MSNBC's Joe Scarborough exclaimed, "Oh shut up. You are a disgrace," adding, "You are a disgrace for normalizing Donald Trump's behavior."

Graham has said of Mr. Trump, "I never said he was the best example of the Christian faith. He defends the faith. And I appreciate that very much." And he said that the president "has admitted his faults and has apologized to his wife and daughter for things he has done and said. And he has to stand before God for those things."

Buttigieg has been feuding with Vice President Mike Pence over his opposition to gay marriage and gay rights. "If me being gay was a choice, it was a choice that was made far, far above my pay grade," Buttigieg said at an LGBTQ Victory Fund brunch earlier this month. "And that's the thing I wish the Mike Pences of the world would understand — that if you've got a problem with who I am, your problem is not with me. Your quarrel, sir, is with my creator."

He has also suggested that suffers from his own Christian failings in supporting Mr. Trump. "How could he allow himself to become the cheerleader of the porn star presidency? Is it that he stopped believing in scripture when he started believing in Donald Trump?" he said at a CNN town hall in March.

In 2015, when both Buttigieg and Pence were serving in Indiana, Pence, then the governor, signed a law that critics said unfairly targeted members of the LGBTQ community. Months later, during his mayoral re-election bid, Buttigieg came out as gay. The law was eventually rolled back amid a national outcry.

Last year, Buttigieg married teacher Chasten Glezman, and should he win the presidency, the two would be the first gay first couple in the White House.

Buttigieg has not yet responded to Graham's remarks.