In the centuries before Constantine "Christianized" the Roman Empire, the church was wary of politicians. Lists of professions that would bar a person from making gifts to the church, becoming a priest, or even being baptized included pimps, makers of idols, wrestlers, flute and zither players—and magistrates who "wear the purple" or do not deal justly.

One of these documents declares: "Anyone who is raised to a prefect's authority or to the magistracy and who does not put on the justice of the gospel, let him be cut off from the flock and let the bishop not pray with him." Church leaders have been admonishing politicians ever since. A group of United Methodist bishops sought to dissuade President Bush from going to war in Iraq, but he refused to meet with them. And now presidential hopeful John Kerry has become the lightning rod for hierarchical rebuke as the most prominent of many Catholic politicians whose pro-choice commitments conflict with church teaching.

Recognizing that Kerry's ideologically consistent support for abortion rights conflicts with church teaching, the Roman Catholic Archbishop of St. Louis warned the politician not to present himself for Communion while campaigning in Missouri. Home in Massachusetts for Easter, Kerry did not receive Communion at a parish church, but at a center "in the Catholic tradition" known for its progressive politics.

Eventually, the Vatican's Cardinal Arinze told reporters that a politician who is "unambiguously pro-abortion" is "not fit [to receive Communion]. If he shouldn't receive it, then it shouldn't be given to him." Arinze would not comment directly on Kerry.

Kerry routinely invokes separation of church and state to explain his position. A typical statement seriously ...