Speaking Saturday at a Catholic high school in Metairie, U.S. Supreme Court Justice Antonin Scalia criticized other members of the court for what he said is a false understanding of the nature of religious freedom and the relationship between church and state.

He said the idea that government must be neutral between religion and unbelief is not grounded in the country’s constitutional traditions and that God has been good to the United States because Americans honor him.

Scalia was speaking at Archbishop Rummel High School at an event sponsored by the school and Catholic Community Radio as an early commemoration of Religious Freedom Day.

The day has been celebrated annually on Jan. 16 since 1993, when outgoing President George H.W. Bush issued a proclamation declaring it. A similar presidential declaration has been issued every year since then.

Before the conservative jurist’s speech began, New Orleans Archbishop Gregory Aymond offered a prayer for the crowd of about 600 people attending the event.

Scalia, at 79 the court’s longest-serving justice, then launched into a self-described “sermon” on one of his favorite topics: the high court’s rulings on the separation of church and state.

Though most judges tend to shy away from controversial public speeches, Scalia, as usual, did not hold his tongue.

For instance, he gave the audience a text to reflect upon. He said those old enough to remember Robert F. Kennedy’s 1968 campaign for president might remember these words: “Some men see things as they are and say, ‘Why?’ I dream things that never were and say, ‘Why not?’ ”

Using that as a framework, Scalia characterized many of his court colleagues as dreamers who see things as they never were — and the U.S. Constitution as it really wasn’t.

He said he would concur with their principle of treating religion and non-religion as equals if Congress enacted it by statute. “But don’t cram it down the throats of an American people that have always honored God,” he said.

Religious Freedom Day marks the anniversary of the 1786 adoption of the Virginia Statute of Religious Freedom, written by Thomas Jefferson, so that Virginians could choose their own faith instead of being compelled to worship in the Church of England, the official state church.

The statute is considered a precursor to the First Amendment of the U.S. Constitution, which says that Congress “shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof.”

Scalia, a devout Catholic who attended a Jesuit high school, told Saturday’s crowd about his days at P.S. 13 in Queens, New York, during the 1940s, when he and his public school classmates had “early release” once a week, when they could leave school an hour early to go to their churches and receive religious instruction.

A decade later, the American Civil Liberties Union sued over the practice of allowing early releases for religious reasons. But the U.S. Supreme Court upheld the practice in a 1952 decision written by Justice William O. Douglas, a liberal who — Scalia quipped — was not known for being either religious or conservative.

Yet Scalia quoted from Douglas’ decision. “We are a religious people whose institutions presuppose a Supreme Being,” he read. “When the state encourages religious instruction … it follows the best of our traditions.”

Now, a half-century later, Scalia said, the same court uses all sorts of tests and principles to decide whether the government is favoring religion over non-religion instead of remaining neutral.

Scalia then turned to history. The same First Congress that introduced the Bill of Rights also instructed President George Washington to proclaim a national day of thanksgiving and prayer, he said. “But we can’t favor religion over non-religion?”

Moving to another constitutional issue, he said courts continue to insist that search and seizure is unconstitutional unless a warrant is obtained. “We made that up,” he said, adding that many exceptions allow searches without warrants, including so-called search-and-frisk stops and traffic stops. “It would be more accurate to say that a warrant is generally required for a home and sometimes required elsewhere,” he said.

Again quoting from his “text” — “I dream of things that never were and say, ‘Why not?’ ” he then quipped, “That seems to be what my court does.”

In a 2003 speech marking Religious Freedom Day, Scalia criticized a lower court’s decision about a Pledge of Allegiance case brought by an atheist father on behalf of his daughter, a public school student in California. The 9th U.S. Circuit Court of Appeals had ruled that Congress made the pledge unconstitutional when it added the words “under God” to its text in 1954. Scalia described that as an attempt to “exterminate (religion) from the public forum by judicial fiat.”

At the end of his remarks, Scalia circled back to the phrase he’d asked the audience to ponder, which actually originated in a George Bernard Shaw play, “Back to Methuselah,” he said.

The original line, as written by Shaw, was “You see things; and you say, ‘Why?’ But I dream things that never were; and I say, ‘Why not?’” Scalia said.

Then he paused. In Shaw’s play, he said, the line “was spoken by a serpent, addressing a woman named Eve.”