What Bernie Sanders needs, said the headline over a column in — of all places — the Jewish Forward, is a “come-to-Jesus moment.” I don’t mind saying that I almost fell out of my socks.

The Forward seems to be referring to the need for Mr. Sanders to share his vision, what I’d call his true beliefs. Its columnist, J.J. Goldberg, wants a “big picture” oration, like Martin Luther King’s “I have a dream” speech.

Mr. Goldberg suggests that Mr. Sanders tell us how he’s going to bring the country together and where he’s going. An apt suggestion, in my view. I’d also like to know from where Sanders is coming.

The idea of an atheistic Jewish socialist from Vermont (by way of Brooklyn) doesn’t seem to nonplus the voters, at least in the Democratic Party. Good for them. America eschews religious tests as a matter of law and principle.

Yet for a man who wants to be the first Jewish president, Sanders certainly seems to be bent on avoiding the subject of the time he spent in Israel. It strikes me as past due for him to explain himself.

It’s long been known that the only self-professed socialist in the Senate spent time on a kibbutz, or communal farm. Nothing wrong with that. But so tight-lipped has Mr. Sanders been about it that the Israeli daily Haaretz put its reporters on the mystery.

“One of Israel’s best-kept secrets” is how the paper described the name of Mr. Sanders’ kibbutz. At one point it thought it had found the senator’s name in a kibbutz archive, but it turned out to be a Bernice Stamder.

Haaretz finally solved the mystery last week, with the discovery, in its own files, of an interview Mr. Sanders gave to the paper back in 1990. In it, the future senator speaks of spending time on a kibbutz called Shaar Haamakim.

The kibbutz, according to the Times of Israel, belonged to an Israeli political party called Mapam, which had in the 1950s “been a communist, Soviet-affiliated faction.” It said kibbutz members “had admired Joseph Stalin until his death.”

They would, the Times of Israel reports, “celebrate May Day with red flags.” They spoke of “controlling the means of production, taking from each according to his abilities and giving to each according to his needs.”

It may be that by 1963, when the future senator spent several months on the kibbutz, the place had calmed down. Yet come 1990, when Mr. Sanders was interviewed by Haaretz, he was still none too happy with Israel — or America.

Or, as the Jewish Telegraphic Agency characterized it, Mr. Sanders was “a sharp critic of the foreign policies of the Reagan and first Bush administrations.” Particularly in respect to Central America.

Mr. Sanders told Haaretz that he was “embarrassed by Israel’s involvement.” Why? Because Israel was, according to the JTA account, “a front for the American government.”

OK. A lot of people were upset with the American government.

People who are embarrassed that other countries are helping America, however, don’t usually stand for president. After all, the very job of the president himself is to front for America.

Mr. Sanders claimed his beef was that Israel was delivering arms to “repressive regimes,” according to JTA’s account. It quotes Mr. Sanders as saying he’d “like to see greater pressure on Israel to compromise on the Palestinian issue.”

There is a whole cottage industry of Jews plumping for the Palestinians. But what had we been up to in Central America in 1990? That was the year in which, because of America, democracy finally triumphed.

It was a year to feel particularly good about America. The Nicaraguan people finally got to go to the polls in a free election. (They promptly ousted the Sandinista regime that had set up a Marxist dictatorship in league with the Soviet Union.)

The joy was not limited to Central America. The Berlin Wall came down in 1989, signaling that it was but a matter of time before the entire Soviet Union would collapse and be cast, as Reagan once put it, into the ash heap of history.

No one is saying that Mr. Sanders was a communist himself (and even many idealists who fell for communism got over it). All the more reason to ask what Mr. Sanders was doing complaining about America and the Israelis.

Mr. Sanders may not have to come to Jesus. But he could come clean.

This column first appeared in the New York Post.