It has become a cliché for Christians to ask, What would Jesus do? But as we close out one of the nastiest campaigns in memory, it might be timelier to ask, For whom would Jesus vote? Many Christians think they at least know for whom the Lord would not vote, based on one issue.

In September, Illinois Republican Senate candidate Alan Keyes stated that Jesus would not vote for rising star Democrat Barack Obama, his opponent, because of Obama's earlier vote in the state Senate against a bill requiring doctors to provide medical care to infants born alive after attempted abortions. James I. Lamb, executive director of the pro-life group Lutherans For Life, also thinks he knows. "A candidate who favors abortion should be disqualified from receiving a Christian's vote," Lamb says. "A vote for a pro-abortion candidate implicates the voter in the destruction of children created by God and for whom Jesus died."

Over the summer, Cardinal Joseph Ratzinger, who heads the Vatican's Congregation for the Doctrine of the Faith, gave such single-issue thinking more nuance. In a memo to Cardinal Theodore McCarrick of Washington, D.C. (McCarrick leads a task force on Catholic politicians), Ratzinger said Catholics may vote for a politician who supports abortion rights if (1) abortion is not the reason for their vote, and (2) they have "proportionate reasons" (in other words, if the candidate's positions on other issues outweigh his or her stand on abortion).

But how do you measure whether a candidate's good on other issues outweighs his or her bad on the question of human life? As Archbishop Raymond Burke of St. Louis said in reaction to the memo, "What is a proportionate reason to justify favoring the taking of an innocent, defenseless human ...