MOUNT PLEASANT, Iowa — In the days after immigration agents raided a dusty concrete plant on the west side of town, seizing 32 men from Mexico and Central America, the Rev. Trey Hegar, pastor of the First Presbyterian Church, got into an impassioned argument on his Facebook page.

“The Bible doesn’t promote helping criminals!!!!” a Trump supporter wrote.

Mr. Hegar answered with Leviticus: “When a stranger resides with you in your land, you shall not do him wrong. The stranger who resides with you shall be to you as the native among you, and you shall love him as yourself, for you were aliens in the land of Egypt.”

The Trump supporter came back with the passage in the Gospel of Mark about rendering unto Caesar the things that are Caesar’s, and added for good measure: “Immigration laws are good and Godly! We elected our leaders and God allowed it.”

President Trump’s immigration crackdown has been promoted with biblical righteousness by senior members of his administration, including Attorney General Jeff Sessions. And in heartland communities where the president is popular, the crackdown is often debated — by supporters and critics alike — through the lens of Christian morality.