Many Americans were shocked last week when Attorney General Jeff Sessions turned to the Bible — specifically, Paul’s epistle to the Romans — to justify President Trump’s policy of separating migrant children from their parents. This scriptural justification for a political decision should not have surprised anyone, because Mr. Trump’s administration has consistently treated the separation of church and state as a form of heresy rather than a cherished American value.

Attacks on the wall of separation established by the founders — which the religious right likes to call “a lie of the left” — are nothing new. What has changed under Mr. Trump is the disproportionate political debt he owes to extreme religious conservatives, whose views on church-state issues — ranging from the importance of secular public education to women’s and gay rights — are far removed from the American mainstream.

The very meaning of the phrases “religious liberty” and “religious freedom”— traditionally understood as referring to the right of Americans to practice whatever faith they wish or no faith at all — is being altered to mean that government should foster a closer relationship with those who want to mix their Christian faith with taxpayer dollars. This usage can be found in numerous executive orders and speeches by Mr. Trump and his cabinet members. Changes in language have consequences, as the religious right’s successful substitution of “pro-life” for “anti-abortion” has long demonstrated.

Religion-related issues, especially if buried in lengthy government documents, can often seem obscure, but they dominated the news at the end of June, when the Supreme Court upheld Mr. Trump’s travel ban targeting majority-Muslim countries and struck down a California requirement that anti-abortion, state-licensed pregnancy clinics provide notice to their clients that abortion is an option. These significant rulings were immediately overshadowed by the retirement from the court of the frequent swing voter Anthony M. Kennedy, which now gives Mr. Trump the opportunity to nominate a predictable religious conservative who would most likely support the overturning of Roe v. Wade.