(RNS) Donald Trump put a couple of bills in the Communion plate.

“I thought it was for offering,” he explained and laughed, according to a report by The Associated Press.

The accidental offering took place during a church service Trump attended with his wife, Melania, at the nondenominational First Christian Church’s Orchard Campus in Council Bluffs, Iowa, on Sunday (Jan. 31). Trump also took Communion at the service.

The presidential candidate, a Presbyterian who is trying to appeal to Christian voters in the Iowa caucuses Monday (Feb. 1),  has made religious gaffes before.

Last month, during a speech at Liberty University, founded by the Rev. Jerry Falwell, Trump referred to “Two Corinthians,” the book of the Bible better-known as “Second Corinthians.”

Trump’s two main rivals for the GOP nomination — Sens. Ted Cruz and Marco Rubio — have more established ties with evangelicals than Trump, who still leads among Republican evangelical voters.

READ: 5 faith facts about Donald Trump: A Presbyterian who collects Bibles

(Lauren Markoe is a national reporter for RNS)