When Jesus was pressed to identify the most important commandments in all of Jewish law, his answer was both a summons and a rebuke. There were, quite literally, hundreds of commands to choose from. Yet behind them all, he said, was this: Love God with all your heart, love your neighbor as yourself. "All the law and the prophets hang on these two commandments." That's worth keeping in mind as the spectacle in Alabama over the posting of the Ten Commandments plays itself out in the courts.

Indeed, the rhetoric of many activists suggests that a deeply rooted temptation in the Christian church is alive and well: the impulse to reduce the faith to its externals.

Judge Roy Moore is surely right that the presence of the Decalogue in a state courthouse is no violation of the First Amendment. And it's a matter of history, as he says, that the Ten Commandments supplied much of the bedrock of the Western legal tradition. It's hard not to admire Moore's defiant stand for God's moral norms in public life. Yet he and his supporters, nearly all evangelical Christians, are on dangerous ground when they appear to use the posting of the Commandments as a litmus test for the faithful. In defending their willingness to disregard a federal court ruling, they argue thus: "We must obey God's law, not man's law."

Since when did the public display of the Ten Commandments become the eleventh commandment? This style of argument hints at a tension that has shaped Protestant Christianity since the Reformation.

Evangelicals hardly need to be reminded that Martin Luther assailed the Catholic Church for confusing religious observances with simple faith in Christ and his death on our behalf. For every Protestant since, the gospel of grace cannot be identified ...