In ancient Greece and Rome, human life had very little value. The Spartans left weak children to die on the hillside. Infanticide was common, as it is even today in many parts of the world. Fathers who wanted sons had few qualms about drowning their newborn daughters. Human beings were routinely bludgeoned to death or mauled by wild animals in the Roman gladiatorial arena. The greatest of the classical thinkers, from Seneca to Cicero, saw nothing wrong with these practices. Christianity banned them, and Christianity introduced the moral horror we now feel when we hear about them.

Women had a very low status in ancient Greece and Rome, as they do today in many cultures, notably in the Muslim world. Aristotle expressed the view of many when he wrote that in men reason finds its full expression. In children, according to Aristotle, reason is present but undeveloped. In women, he wrote, reason is present but unused. Such views are common in patriarchal cultures. And, of course, they were prevalent in the Jewish society in which Jesus lived. But Jesus broke the taboos. From society’s point of view and even from some of his male disciples’ point of view, Jesus scandalously permitted women (even of low social status) to travel with him and be part of his circle of friends and confidantes.

Christianity did not contest patriarchy, but it elevated the status of women within it. The Christian prohibition of adultery—a sin viewed as equally serious for men and women— placed a moral leash on the universal double standard that commanded women to behave themselves while men did as they pleased. Unlike Judaism and Islam, which treated men and women unequally in matters of divorce, Christian rules on the matter were identical for women and men. So dignified was the position of the woman in Christian marriage that women predominated in the early Christian church, as in some respects they do even today. As a result, the Romans scorned Christianity as a religion for women.

We encounter in the Middle Ages a new development—the idea of courtly love. For the first time in history, the woman who was a knight’s object of love was raised to a high status. In fact, her status was higher than that of the man pursuing her. Women were increasingly viewed as companions whose conversation was prized and whose company was avidly sought. Chaucer’s independent-minded Wife of Bath isinconceivable in any other culture of the fourteenth century. Courtesy, the habit of treating women with deference, was invented by Christianity. Social life involving men and women began in the late Middle Ages. Moreover, as family life came to be seen as the central locus of human happiness, the role of the mother in preserving the household and ensuring the education of children became more highly valued.

Against these advances, atheists counter with another issue: slavery. “Consult the Bible,” Sam Harris writes in Letter to a Christian Nation, “and you will discover that the creator of the universe clearly expects us to keep slaves.” Steven Weinberg notes that “Christianity… lived comfortably with slavery for many centuries.” These atheist writers are certainly not the first to fault Christianity for its alleged approval of slavery. But slavery pre-dated Christianity by centuries and even millennia. It was widely practiced in the ancient world, from China and India to Greece and Rome, and most cultures regarded it as an indispensable institution, like the family. For centuries, slavery needed no defenders because it had no critics. Even the Bible does not condemn slavery outright, with Paul in Ephesians 6:5 and other passages urging slaves to obey their masters and urging masters to be kind to their slaves.