Donald Trump is now in a holy war with the Pope.

On his way back to the Vatican after concluding a six-day tour of Mexico, Pope Francis waded into the 2016 Republican primaries by declaring that Donald Trump is “not Christian.”

“A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian,” he told a reporter.

Trump was not going to take that, er, kneeling down. He predicted the Vatican would be attacked by ISIS, claimed that the Mexicans are “using the Pope as a pawn,” and said it was “disgraceful” for a “religious leader to question a person’s faith.” His adviser then burned the Vatican for its hypocrisy on Twitter.

So you can now officially add the Pope to Trump’s list of enemies, which include, but are in no way limited to, Jeb Bush, Samuel L. Jackson, Morty Zuckerman, and George Will.