Professor Clough’s book, which came out in 2012, is one of two recent major Christian treatises on animal rights. The other, published this year, is “For Love of Animals: Christian Ethics, Consistent Action,” by Charles Camosy, a Fordham professor and a Catholic who has given up meat — though he still eats fish, “half because Jesus Christ ate fish, and half because I am too weak to give up my grandmother’s tuna spaghetti sauce,” he told me.

In “For Love of Animals,” Dr. Camosy links his concern for animals to his beliefs on abortion, arguing that the Catholic ethics of respect for life and care for the vulnerable should make us reconsider how we treat animals. The Catholic catechism permits meat eating, he told me, “but with two qualifications: we owe animals kindness, and it’s wrong to cause them to suffer needlessly.” The clear implication, he said, is that except for the poor who can’t get food other ways, everyone has a duty at least to avoid eating factory-farmed animals.

Mary Eberstadt, a political conservative and a Catholic, wrote the introduction to Dr. Camosy’s book and has praised it in National Review. After being “in and out of vegetarianism for decades,” as she said in an email this week, she now eats fish. Her choices were influenced, she said, by the vegetarian Leo Tolstoy’s 1909 essay about a slaughterhouse, and by “Dominion: The Power of Man, the Suffering of Animals, and the Call to Mercy,” the 2002 book by Matthew Scully, a conservative who was raised Catholic and wrote speeches for President George W. Bush.

Although there is an old, small tradition of Christian vegetarianism, the modern field of Christian animal rights can be dated to 1976, when Andrew Linzey, a theology student at King’s College, London, looked around at his fellow Christians and was struck by how little they cared about cruelty to animals. “I was puzzled by the indifference of my teachers to the issue and the general thoughtlessness of Christians,” Professor Linzey, who now teaches at Oxford, said in an email this week. So he wrote “Animal Rights: A Christian Assessment,” which was published in 1976, while he was still a student.

Although Professor Linzey’s book caused a sensation in Christian circles, animal welfare became mainly a secular cause. Christians focused on other battles — from the right, abortion; from the left, war and poverty — while some secular animal-rights activists were suspicious of Christianity, concurring with Peter Singer’s claim, in his 1975 classic, “Animal Liberation,” that Christian teaching about man’s dominion had been an impediment to animal rights.