Pope says Trump 'not Christian,' Trump calls comment 'disgraceful'

Pope Francis leads the First Vespers and Te Deum prayers in Saint Peter's Basilica at the Vatican December 31, 2015 and U.S. Republican presidential candidate Donald Trump (R) holds up a copy of the Bible he said his mother gave him as a youth during a campaign rally in Council Bluffs, Iowa, December 29, 2015 in a combination of file photos. REUTERS/Max Rossi/Lane Hickenbottom/Files

NEWBERRY, S.C. (Reuters) - Pope Francis forcefully injected himself into the U.S. presidential campaign on Thursday, assailing Republican candidate Donald Trump's views on U.S. immigration as "not Christian" in a sign of growing international concern at the billionaire businessman's election prospects.

Trump struck back. No stranger to controversy, the longtime party front-runner in national opinion polls dismissed the leader of the world's Roman Catholics as "disgraceful" for questioning his faith. He said he was a proud Christian.