The two sides engaged in a fierce battle over gay marriage may not agree on much, but they come together on this: the institution of marriage faces a crossroads. For one camp, gay marriage marks the culmination of years that have slowly but surely weakened marriage. These conservatives have drawn a line in the sand and refuse to relent this time. For the other camp, gay marriage symbolizes a different sort of Rubicon. After a succession of smaller victories in the sexual revolution, these innovators now seek to inflict a crippling blow to traditional marriage by abolishing the two-gender definition that has guided society thus far.

Yet, as usual in America's myopic debates, not many on either side realize that the struggle over defining marriage has been going on for centuries already.

For example, during the early church period, some religious leaders denounced marriage altogether, while others advocated polygamy. And during the Reformation, Henry VIII infamously flouted the explicit teaching the Roman Catholic Church to seek a divorce.

Not surprisingly, the human tendency over the years has been to reshape marriage to fit temporal desires. But before concerned Christians can defend a "traditional, Christian definition" of marriage as the appropriate, healthy standard for society at large, we need to know what that standard looks like and how it has developed.

A Brave New World for Marriage Determining the purpose of marriage was one of the early church fathers' most daunting challenges. They discovered rich guidance in Jesus' teachings and Paul's writings but sometimes struggled to shed pagan preconceptions and interpret Old Testament models. Compounding their difficulties, some influential religious leaders offered unorthodox ...