"I brought my Bible. You know, it's the First Presbyterian Church, Jamaica (Queens) and this was written by my mother, with my name, with my address, with everything," he said as he held up his Bible and opened it for the crowd. "I saw this and I had to bring it."

Trump also launched into a defense of Christmas to the crowd.

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"The word 'Christmas' -- I love Christmas. I love Christmas. You go to stores now, you don't see the word 'Christmas.' It says 'Happy Holidays' all over," Trump said to applause. "Remember the expression, 'Merry Christmas?' You don't see it anymore. You're going to see it if I get elected, I can tell you right now."

But the clear Republican front-runner fell flat at times during his talk, drawing limited applause and even boos for calling Sen. Marco Rubio a "clown" over illegal immigration. The boos continued as Trump talked through them, saying, "I've been so nice to him."

Trump later took to Twitter to continue his attacks on Rubio, his latest target in the Republican presidential field.

".@MarcoRubio is weak on illegal immigration and will allow anyone into the country.....," Trump tweeted.

Trump's faith has been a topic of discussion on the campaign trail. He drew heat over the summer during a stop in Ames, Iowa, when he said he had not sought forgiveness from God. And Trump, who once referred to communion as "my little wine and my little cracker," has called the Bible his favorite book, but declined to name his favorite verse when pressed by Bloomberg last month.

RELATED: Conservatives boo Trump after Rubio 'clown' insult

His speech Friday also comes at a somewhat rocky time for his campaign.

The latest CNN/ORC national poll showed that he's lost some support after the second GOP debate as outsider candidates like Carly Fiorina gain steam, though he still retains a commanding lead over the field.