A trio of Republican presidential candidates said Sunday that questions about Mitt Romney and his Mormon faith shouldn’t play a role in the race for the GOP nomination.

Former House Speaker Newt Gingrich said on CBS’s “Face the Nation” that a Texas pastor who recently called Mormonism "a cult" and said Romney was not a Christian was unwise and inappropriate.

“None of us should sit in judgment on somebody else’s religion,” Gingrich said.

The comments came after Robert Jeffress, the leader of a Dallas megachurch, blasted Romney and his faith while endorsing Gov. Rick Perry of Texas at the Values Voter Summit in Washington.

Herman Cain, also appearing on “Face the Nation,” agreed with Gingrich, and repeated a line he made on other Sunday shows – that none of the candidates were running for “theologian in chief.”

He added that voters could be interested in a candidate’s values without worrying about their specific faith.

“Getting into whether they’re more Christian than another group – I don’t think that’s relevant to this campaign,” Cain said about Mormons.

Elsewhere, former Sen. Rick Santorum of Pennsylvania said he also took Romney at his word that he was a true Christian – taking a potshot at Senate Majority Leader Harry ReidHarry ReidConservative Senate candidate calls on GOP to end filibuster Ex-Reid aide: McConnell's 'original sin' was casting ObamaCare as 'partisan, socialist takeover' GOP faces growing demographic nightmare in West MORE (D-Nev.), also a Mormon, in the process.

“Every Mormon I know is a good and decent person, has great moral values and is by and large – exception of Harry Reid – by and large pretty consistent in the values that I share and the things I want to see happen to this country,” Santorum said on “Fox News Sunday.”