WASHINGTON — “For many today, religious liberty is not a cherished freedom,” Justice Samuel A. Alito Jr. told the Federalist Society, the conservative legal group, in November. “It pains me to say this, but, in certain quarters, religious liberty is fast becoming a disfavored right.”

Those quarters do not include the Supreme Court, which has become far more likely to rule in favor of religious rights in recent years, according to a new study that considered 70 years of data.

The study, to be published in The Supreme Court Review, documented a 35-percentage-point increase in the rate of rulings in favor of religion in orally argued cases, culminating in an 81 percent success rate in the court led by Chief Justice John G. Roberts Jr.

“Plainly, the Roberts court has ruled in favor of religious organizations, including mainstream Christian organizations, more frequently than its predecessors,” wrote the study’s authors, Lee Epstein of Washington University in St. Louis and Eric A. Posner of the University of Chicago. “With the replacement of Ruth Bader Ginsburg with Amy Coney Barrett, this trend will not end soon and may accelerate.”

(The court led by Chief Justice Earl Warren, from 1953 to 1969, supported religion just 46 percent of the time. That grew to 51 percent under Chief Justice Warren E. Burger, from 1969 to 1986; then to 58 percent under Chief Justice William H. Rehnquist, from 1986 to 2005; and finally jumped to just over 81 percent under Chief Justice Roberts, who joined the court in 2005.)

The kinds of cases the court is hearing have changed, too. In the Warren court, all of the rulings in favor of religion benefited minority or dissenting practitioners. In the Roberts court, most of the religious claims were brought by mainstream Christians.

The five most pro-religion justices all sit on the current court, the study found.

“The justices who are largely responsible for this shift are Clarence Thomas, Samuel Alito, Neil Gorsuch, John Roberts and Brett Kavanaugh,” the study’s authors wrote. “While there are some differences among these justices, and Kavanaugh has been involved in only a handful cases, they are clearly the most pro-religion justices on the Supreme Court going back at least until World War II.” All are Republican appointees.

In the last term alone, the court sided with Christian religious groups in three argued cases. The court ruled that state programs supporting private schools must include religious ones, that the Trump administration could allow employers with religious objections to deny contraception coverage to female workers and that employment discrimination laws do not apply to many teachers at religious schools.

And the court will soon decide whether Philadelphia may bar a Catholic agency that refused to work with same-sex couples from screening potential foster parents.

After Justice Barrett joined the court, it changed positions on the one question on which religious groups had been losing: whether governors could restrict attendance in houses of worship to address the coronavirus pandemic.

There has been a similar shift in the entire federal judiciary in cases on the constitutional protection of the free exercise of religion.

Protecting that right, as Justice Alito pointed out in his speech, used to be a bipartisan commitment. In 1990, when the Supreme Court cut back on protections for free exercise, with Justice Antonin Scalia writing the majority opinion, Congress responded with the Religious Freedom Restoration Act.

“The law had almost universal support,” Justice Alito said. “In the House, the vote was unanimous. In the Senate, it was merely 97 to 3, and the bill was enthusiastically signed by President Clinton.”

Earlier studies, covering 1996 to 2005 and 2006 to 2015, found that judges’ partisan affiliations, as reflected by political parties of the presidents who appointed them, were not significantly tied to their votes in free exercise cases.

Zalman Rothschild, a fellow at the Stanford Constitutional Law Center, updated that data in a second study, to be published in The Cornell Law Review. He found that things had changed.

“The politicization of religious freedom has infiltrated every level of the federal judiciary,” Mr. Rothschild wrote.

In the five years through the end of 2020, he wrote, federal judges’ partisan affiliations had become powerfully correlated to their votes. “And when the pandemic struck, resulting in widespread lockdowns of religious houses of worship,” he wrote, “the unprecedented number of constitutional free exercise cases brought in such a condensed span of time forced that partisanship into sharp relief.”

Even putting aside cases concerning the pandemic, a big partisan gap has opened in free exercise cases. Judges appointed by Democrats sided with religion 10 percent of the time in such cases in the last five years, compared with 49 percent for ones appointed by Republicans and 72 percent for ones named by President Donald J. Trump.

The numbers were even starker, Mr. Rothschild wrote, in cases concerning restrictions meant to combat Covid-19. Through the end of last year, not a single judge appointed by Democrats sided with religion in those cases, while 66 percent of judges appointed by Republicans and 82 percent of judges appointed by Mr. Trump did.

What changed in just the last five years? It is probably no coincidence that the court established a constitutional right to same-sex marriage in 2015.

More generally, claims of religious freedom, brought mostly by Christian groups, have increasingly been used to try to limit progressive measures like the protection of transgender rights and access to contraception. On top of that, a culture war erupted about how best to address the coronavirus.

In 2018, Justice Elena Kagan accused the court’s conservative majority of “weaponizing the First Amendment,” of using its protection of free expression “to intervene in economic and regulatory policy.”

Professor Epstein said something similar was afoot in the court’s religion decisions. “Just as the majority has weaponized free speech in service of business and conservative interests,” she said, “it’s using the religion clauses to privilege mostly mainstream religious organizations.”