If you want to understand white evangelicalism in the age of Trump, you need to know Robert Jeffress, the pastor of First Baptist Church in Dallas.

Jeffress is not a household name in the United States, known mainly in Southern Baptist circles. But he has recently gained national attention as a “court evangelical” — my term for a Christian who, like the attendants and advisers who frequented the courts of monarchs, seeks influence through regular visits to the White House.

The court evangelicals are changing the religious landscape in the United States. The Trump presidency is only six months old, but it is already beginning to alter long-standing spiritual alignments. It seems as though Christians are not changing Trump, but rather that Trump could be changing Christianity. ...

Historians can trace the court evangelical phenomenon to the early 1970s, when the popular evangelist Billy Graham remained loyal to President Richard Nixon, to quote biographer Grant Wacker, “long after most Americans smelled a rat.” When Nixon resigned in shame, Graham was embarrassed. He admitted that “Nixon’s magnetism clouded his judgment.” In 1993, Graham “urged young evangelists to avoid his mistake.”

In the 1980s, Ronald Reagan appealed to evangelical concerns about big government, the threat of communism and legalized abortion. Christian political movements such as the Moral Majority and the Christian Coalition educated an entire generation of evangelicals to believe that Christian political engagement was tied solely to electing Republican politicians and controlling the Supreme Court.

Very few evangelicals criticized these efforts to advance a Christian agenda through politics; those who did could not compete with the economic prosperity and Cold War victories that Reagan delivered. But some who rode this wave of evangelical political power had a hard time sleeping at night.

In 1999, two architects of the Moral Majority — Michigan pastor Ed Dobson and syndicated columnist Cal Thomas — published “Blinded by Might: Can the Religious Right Save America?” As they reflected on 20 years of their own political activism, Dobson and Thomas concluded that the movement to change the world through politics had failed. All that was left in the wake of a generation of political crusading was a cast of characters who had succumbed to the “aphrodisiac” of power and had sacrificed their spiritual authority in the process.

Around the time Dobson and Thomas published their book, the Christian Right was mobilizing against the many infidelities of Bill Clinton. James Dobson (no relation to Ed), a popular radio host known best for founding the Colorado Springs ministry Focus on the Family, chided Clinton for his adulterous affair with White House intern Monica Lewinsky and argued forcefully, in a September 1998 letter to supporters, that Clinton did not deserve evangelical support because he was a liar, immoral, lacking in character and motivated by “raw political power.”

Today Dobson, the man most responsible for promoting the long-standing GOP “family values” agenda, supports Trump. ...