Conservative commentator Glenn Beck on Thursday predicted that church attendance would shrink by half in the next five years if the Supreme Court declares gay marriage bans unconstitutional.

Beck made the prediction after interviewing Aaron and Melissa Klein, the owners of an Oregon bakery who are facing fines for refusing to make a cake for a lesbian couple's 2013 commitment ceremony. (At the time, gay couples could not marry in Oregon.)

A high court ruling striking down the bans will lead to government seizures of church property and the persecution of Christians, Beck said.

“Mark my words,” Beck told listeners, “if gay marriage goes through the Supreme Court and gay marriage becomes fine and they can put teeth in it so now they can go after churches, like the president's lawyer says, 50 percent of our churches will fall away. Meaning, within 5 years, 50 percent of the congregants will fall away from their church because they won't be able to take the persecution.”

Beck continued: “Mark my word, within 5 years, 50 percent of the people that you sit next to in church will not be there. And not because [they'll say,] 'You know what, I think [gay marriage is] fine,' [but] because they'll say, 'I can't do that. I'll lose my job. People are picketing my house. I just can't do that.'”