Republican presidential frontrunner Donald Trump is making heads turn as he continues to gain support from evangelicals despite the impression that "he personifies greed, embodies pride, [and] radiates lust ...[among other] "seven deadly sins," as one New York Times columnist writes.

The key to Trump's success, as the latest polls show, is his ability to address issues that are relevant to conservative voters following the first Republican presidential debate last Aug. 6, analysts said.

Trump's post-debate supporters among evangelicals rose 38 percent from 36 percent before the debate, according to MSNBC.

At a campaign in Alabama over the weekend where 30,000 people were in attendance, Trump likened himself to Billy Graham and said, "What's my favourite book? The Bible! The Bible. ... We take the Bible all the way."

Trump previously said he would defend Christianity.

"There's an assault on anything having to do with Christianity," Trump said. "They don't want to use the word Christmas anymore at department stores."

New York Times columnist Frank Bruni is perplexed as to why Trump is gaining support from evangelicals.

"Let me get this straight. If I want the admiration and blessings of the most flamboyant, judgmental Christians in America, I should marry three times, do a queasy-making amount of sexual boasting, verbally degrade women, talk trash about pretty much everyone else while I'm at it, encourage gamblers to haemorrhage their savings in casinos bearing my name and crow incessantly about how much money I've amassed?" he wrote.

Bruni said "polls show him to be the preferred candidate among, not just all Republican voters but also, the party's vocal evangelical subset."

Trump, Bruni wrote, is more popular than former evangelical pastor Mike Huckabee, or Ted Cruz, an evangelical pastor's son.

"What's different and fascinating about the Trump worship is that he doesn't even try that hard for a righteous facade — for Potemkin piety," Bruni said.

"But beyond that? He just about runs the table on the seven deadly sins. He personifies greed, embodies pride, radiates lust. Wrath is covered by his anti-immigrant, anti-'losers' rants, and if we interpret gluttony to include big buildings and not just Big Macs, he's a glutton through and through. That leaves envy and sloth. I'm betting that he harbours plenty of the former, though I'll concede that he exhibits none of the latter," Bruni wrote.

He said evangelicals' support to Trump may be because of his "jingoism they adore. They venerated Ronald Reagan though he'd divorced, remarried and spent much of his career in the godless clutch of Hollywood."

"Maybe their fealty to Trump is payback for his donations to conservative religious groups. Or maybe his pompadour has mesmerised them. It could, in the right wind, be mistaken for a halo. I'm grasping at straws, because there's no sense in the fact that many of the people who most frequently espouse the Christian spirit then proceed to vilify immigrants, demonise minorities and line up behind a candidate who's a one-man master class in such misanthropy."