At one point in Ian Fleming's "Goldfinger," the villain of the title says to James Bond, "They have a saying in Chicago: 'Once is happenstance, twice is coincidence, the third time it's enemy action.'"
Donald Trump met the Goldfinger standard last week, when he raised questions about a rival's religion for the third time this campaign. It is a favorite tactic of the GOP front-runner, to question another's faith, though he doesn't like when his own is questioned.
The most recent target of Trump's innuendo was Mitt Romney, the 2012 GOP nominee who'd been harshly criticizing Trump for weeks. "I have many friends that live in Salt Lake City - and by the way, Mitt Romney is not one of them," Trump told an audience in Salt Lake City last week ahead of the Utah primary. "Are you sure he's Mormon? Are we sure?"
The remark was made in jest, Trump later insisted, in what is also a familiar part of this tactic. Last October, when Trump was being challenged in the polls by Ben Carson, who identifies as a Seventh Day Adventist, Trump mused out loud about Carson's religion.
"I'm Presbyterian. Boy, that's down the middle of the road, folks, in all fairness," he told a crowd in Jacksonville. "I mean, Seventh-day Adventist, I don't know about. I just don't know about."
In an appearance on "Face the Nation" shortly thereafter, Trump denied that he was trying to raise any eyebrows about Carson's faith in order to hurt him with evangelical voters.
TRUMP: I don't know about that. I don't know about what that is. I'm not that familiar with it. I have heard about it, but I'm not that familiar with it. That wasn't meant to be insult, obviously. It's just that I don't know about it.
DICKERSON: OK. So an expression of ignorance, not raising questions about it?
TRUMP: Well, it's a harsh way of putting it, but perhaps I could say it that way, yes, because I just don't know about -- as I said, I don't know about that.
Later in 2015, Trump watched as another rival - Texas Sen. Ted Cruz - crept into the lead in Iowa, buoyed by a strong showing among evangelical Christians. At a campaign event in Iowa in December, Trump once again attempted to sow some doubt on the subject of Cruz's religion.
"Just remember this," he told voters. "You gotta remember, in all fairness, to the best of my knowledge, not too many evangelicals come out of Cuba, OK?"
There is no doubt about Cruz's evangelical bona-fides, of course - his platform and stump speech are grounded firmly in his Christian faith. His father, Rafael, is an evangelical pastor.
Asked about his quip on Cruz and evangelicals during an appearance on "Face the Nation," Trump once again said he meant nothing by it.
DICKERSON: When you say about Senator Cruz not too many evangelicals come out of the Cuba, what does that mean?
TRUMP: Well, it just means that Cuba, generally speaking, is a Catholic country. And you don't equate evangelicals with Cuba. I don't. I think of evangelicals, and I have a -- I guess I am. I'm Presbyterian. I'm Protestant. But I don't see it as coming out of Cuba.
DICKERSON: But you're not questioning whether -- as far as you know, he could be more devout than you are.
TRUMP: It's possible. Certainly, it's possible. I'm not questioning. And I say it in a somewhat smiling manner, but there's a little truth to it.
Trump also questioned Cruz's faith more directly during the South Carolina primary, asking, "How can Ted Cruz be an Evangelical Christian when he lies so much and is so dishonest?"
Trump, for his part, has bristled at any skepticism about his own religious conviction. After Pope Francis suggested Trump's proposal to build a wall along the U.S.-Mexico border was not something a Christian would propose, the GOP candidate took great umbrage.
"No leader, especially a religious leader, should have the right to question another man's religion or faith," Trump declared on Twitter.
When asked on Face the Nation how he could be upset about the Pope questioning his faith, after he so recently questioned Cruz's religion, Trump said, "No, I never questioned Ted's--anything having to do with his religion...I just said you can't lie and hold up a Bible and you can't do that, you just can't do that, it's not appropriate."
The GOP frontrunner has described himself as a strong Christian, even brandishing his Bible at campaign stops. But when he's been pressed for details on his faith, and he hasn't always been exceptionally fluent on the subject.
Trump has said he doesn't ask God for forgiveness, raising eyebrows among Christians who see repentance as a central tenet of their faith. Last August, during an interview with Bloomberg News, Trump declined to cite his favorite Bible verse, saying it was "very personal." And when he was asked which testament he prefers - Old or New - Trump said the two are "probably equal."
Still, in what may be one of the more surprising turns of the 2016 primary, Trump has won strong support from the GOP's religious conservatives. In a CBS News/New York Times poll released this week, Trump won support from 42 percent of white Evangelical Republicans nationwide. Cruz came in second at 35 percent.
Whatever questions may be raised about Trump's faith, they're not hurting him. The same may or may not be true of Trump's questions about his rivals.