Contributing columnist

President Trump's enduring support among evangelical Christians and Mass-attending Catholics befuddles many of his critics. "How could a Christian accept [some presidential action or statement]?" is now a trope. The genuinely confused should realize that for millions of voters, religious liberty remains the overarching issue of the day, the alpha and omega of whether Trump gets a nod of approval or at least a pass. And most of those voters are very well aware that religious liberty is on the Supreme Court's docket this term.

The Supreme Court will soon consider the religious liberty of Jack Phillips in Masterpiece Cakeshop Ltd. v. Colorado Civil Rights Commission. The state of Colorado has said that Masterpiece Cakeshop owner Phillips's refusal to create custom wedding cakes celebrating same-sex wedding ceremonies violates the state's law prohibiting discrimination on the basis of sexual orientation — despite Phillips's policy of refusing to create other confections that collide with his faith, including cakes containing alcohol or celebrating Halloween or atheism.

The case will draw huge attention because it is at the intersection of so many controversies. But the emotions it elicits shouldn't obscure its connection to a large portion of Trump's core support: conservative people of faith.

Evangelicals and Mass-attending Catholics gave the president healthy majorities when they voted last fall, and largely that support has not wavered. For those wondering why, it comes down to the issue at the core of Masterpiece Cakeshop: Will Americans be allowed to practice their religious beliefs without fear of ruin from secular absolutists? In the view of these voters, elites believe every knee must bend to their secular creed, not just on matters regarding sexual intimacy but also on issues of when life begins and when death ought to be optional.

Many people of faith are convinced that their ability to believe, proclaim and practice their genuine faith convictions is in danger not just of ridicule but also of punishment. They hear themselves routinely — and unfairly — compared to racist bigots. They know that racial bigotry in the marketplace is illegal; indeed, they agree with the laws that make it so, such as the Civil Rights Act of 1964, and believe those laws are righteous and, more to the point, constitutional.

Moreover, the vast majority of evangelical and Catholic leaders assert that they, and the president, are not homophobic and that their positions on same-sex marriage do not mean they are anti-gay. They also believe, not without reason, that only Christians, not faithful Muslims, are targeted for refusal to celebrate same-sex unions, in a double standard born of animus toward the Christian community, fear of the Islamic one, or both.

And they expect that, absent a new "test" emerging from the case now before the court, their civil right of free exercise of religion will be erased, quietly and quickly, from the constitutional canon.

That fear drives a lot of politics these days, though it is only dimly perceived by political and media elites for whom the underlying variants of religious belief are at best unusual and sometimes unthinkable. I think that fear explains so much as to be almost too obvious an answer to too many current dilemmas.

Why did Roy Moore win the GOP Senate primary in Alabama? People of faith may not agree with his positions — and most probably don't — but they can count on him being on their side in free-exercise disputes. Why do evangelicals hang in with the president despite his all-too-frequent un-Christian bouts of public disdain toward others, attacks that are at odds with the gospel? Because his judicial appointments — the source of the ultimate protection of faith and the free-exercise clause — are not only solid, they are also better than those of either President Bush.

For many millions of people of faith, Trump is the last line of defense preventing their having to choose between their religious beliefs and full participation in the community and in business.

In short, as the Supreme Court returns to work this week, understand that a lot of the politics of today are driven by its decisions in the past and fear about its decisions in the future. This remains a deeply religious country, and many of its most ardent believers distrust the federal courts and elite opinion-makers to such a degree that they will make common cause with those who will protect their freedom of conscience. The right to "free exercise" isn't just one of many important rights to them; it is the central one by far. Figure that truth into your political analysis, and a lot more becomes clear.