What does court precedent in New York state say about the notion that opposition to same-sex marriage is simply about prejudice? That charge, after all, is being widely made by opponents of Indiana’s religious-freedom law.

I first heard this libel in 2003, when a friend asked me about gay marriage. When the question was put to me, I replied with a question: “What would you say to the Agudath Israel of America?”

That was a reference to America’s largest grassroots organization of fervently Orthodox Jews. It didn’t rattle my interlocutor. “I see them as bigots,” he replied, “just like any other religious fundamentalists.”

The reply shocked me down to the ground, though I, too, hew to a liberal view on gay rights and my friend is an otherwise brilliant fellow. Yet I soon learned that he was not alone. Many view religious Jews — and Christians and Muslims — as bigots.

This is the view that The New York Times attributed to the top Massachusetts judicial panel when in 2003 it became the first state supreme court to lift its state’s ban on gay marriage.

“The ban is simply about prejudice” is how the Gray Lady characterized the court’s ruling. The paper likened the prejudice against same-sex marriage to now-defunct state laws barring interracial marriage.

Yet despite the jackleg preachers, prohibitions on interracial marriage — which were ended by the Supreme Court in 1967 — had no basis at all in the laws brought down from Sinai. And had no conceivable rational basis.

The “rational basis” test was used in 2006 by New York’s highest tribunal, the Court of Appeals, in the case that opened the way to same-sex marriage in the Empire State. The case, known as Hernandez v. Robles, has much to teach.

What the court ruled is that the state constitution leaves to the Legislature the power to either ban or allow gay marriage. The opinion was written by Judge Robert Smith, who, having reached the age of 70, had to retire in December, at the height of his powers.

Writing for the court, Smith rejected the idea that the law then barring gay marriage in New York was comparable to Jim Crow. If the marriage law “were founded on nothing but prejudice,” Smith wrote, the court would “hold it invalid.”

Smith noted racism “has been recognized for centuries — at first by a few people, and later by many more — as a revolting moral evil.” The court acknowledged the history of “serious injustice in the treatment of homosexuals.”

But, the court said, the “traditional definition of marriage is not merely a by-product of historical injustice. Its history is of a different kind. The idea that same-sex marriage is even possible is a relatively new one.”

“Until a few decades ago,” Smith wrote, “it was an accepted truth for almost everyone who ever lived, in any society in which marriage existed, that there could be marriages only between participants of a different sex.”

“A court should not lightly conclude that everyone who held this belief was irrational, ignorant or bigoted,” Smith wrote in one of the court’s most famous sentences, adding: “We do not so conclude.”

Once the court made clear that the Legislature in Albany could use its judgment, activism went into high gear. The Marriage Equality Act was passed in 2011, and it has been widely accepted in the state.

One reason it passed is that the act included a provision that prohibits state courts from penalizing religious institutions for refusing to recognize or sanctify gay marriages or providing services to same-sex weddings.

Should this protection be extended to closely held for-profit family businesses when New Yorkers use them to exercise their religious views? “Yes,” the US Supreme Court seemed to say in the Hobby Lobby case, although that dealt with birth control.

The justices may someday be asked to extend Hobby Lobby to small businesses being pressed on same-sex weddings. In rejecting the idea that a ban on same-sex marriage can be only about prejudice, New York’s high court offered a template.

It led to gay marriage here while protecting religion. It may have had an impact on my friend, too, the one who reckoned religious Jews were bigots. “I don’t really think that anymore,” he e-mailed me over the weekend.

I was glad to discover he’s evolved.

This column first appeared in the New York Post.