Barack Obama has forgiven Joe Biden's erstwhile plagiarism. In so doing, Obama is following a long precedent in both Jewish and Christian ethics. Obama did the right thing.
Ancient Jews relied on a passage from the book of Exodus (34:6-7) to conclude that man's capacity to sin can never exceed God's capacity to forgive. Everything could be forgiven, provided that the sinner contritely confessed and resolved to avoid that mistake in the future.
In the Ashkenazi folk ceremony of tashlikh on Yom Kippur, Jews go to water, preferably a river or a sea full of fish, and shake their clothes as if to cast off every trace of sin, while reciting appropriate verses, such as Micah 7:18-20, which contains the words "and you shall cast [tashlikh] into the depths of the sea all their sins." This one example (among others, such as the scapegoat) supports the idea that the slate could be wiped clean: a sinner could start all over again. Certainly, the Roman Catholic theology of confession also involves centrally the belief that the slate can be wiped clean: After proper atonement, a Catholic's sins are washed away.
Joe Biden is a practicing Catholic, which is to say that Biden comes from a faith community enthusiastically committed to the idea that sins really can be forgiven. Calvinists present a counterexample here; unlike most Jews and Catholics, Calvinists do not believe that all sins can be washed away. Calvinists (and various other Protestant communions) also reject the Catholic distinction between "mortal" (very serious) and "venial" (less serious) sins. Although subsequent Catholic theologians have disagreed with him, it is worth noting that Thomas Aquinas, a lynchpin of the Catholic moral tradition, concluded that only a mortal sin (such as murder or adultery) deserves the name of "sin" (Summa Theologica I-II, q. 88, a. 1).
Were we to take Biden to task for his plagiarism, we would be tarring with the same brush countless other offenders - think of Martin Luther King, Jr. and Doris Kearns Goodwin. (In this piece, I have plagiarized my own book, A History of Sin.) Americans have forgiven King and Kearns, and Americans can forgive Biden as well.
Of course, the exhortation to forgive can extend to other (all?) misdeeds. Think of John Edwards's recent affair or, much more significantly, George W. Bush's alleged lies about weapons of mass destruction. When you ponder all the lives lost in the Iraqi conflict, Biden's having lifted a few words or phrases from someone else's work may seem trifling. That's not to say that Biden never sinned, only that some sins are more drastic than others. In the end, the difference might be moot: To forgive is divine.