Donald TrumpDonald John TrumpGillibrand urges opposition to Kavanaugh: Fight for abortion rights 'is now or never' Trump claims tariffs on foreign nations will rescue US steel industry: report Bannon announces pro-Trump movie, operation team ahead of midterms: report MORE on Wednesday singled out non-Christians during his rally in Iowa, after asking how many were in attendance.

"Raise your hand if you're not a Christian conservative. ... There's a couple people. That's all right. I think we'll keep them, right? Should we keep them in the room, yes? I think so," Trump joked.

The Republican presidential nominee made the remark as he was praising evangelical Christians, stating that he won more support from the group than anyone ever predicted.

"Boy, did I do well with evangelicals," Trump said. He then acknowledged a group called Christian Conservatives for Trump that was a special guest at the rally in Iowa.

"Raise your hand if you are a Christian conservative," he asked as the crowd erupted in applause.

It was then that Trump asked if anyone else was in attendance.

But Trump's joke sparked outrage on Twitter, with many openly questioning his choice of words.