What is the worst sin imaginable? A case certainly could be made for murder. Depriving another human being of life is a fundamental repudiation of God who creates all people in His image. Accordingly, the murderer must forfeit his life. And murder, Maimonides reminds us, is one of those sins for which complete repentance is never possible. So even if the murderer felt remorse, a life taken cannot be replaced, and, without restitution, repentance remains incomplete.
If a repudiation of God is probative, then perhaps blasphemy is the worst imaginable sin. This is the thinking of a goodly part of the Muslim world where execution is demanded of those who demean the prophet Mohammed or his teachings. Asia Bibi, for instance, a Christian mother in Pakistan was convicted of blasphemy and sentenced to death by hanging for daring to drink from a cup reserved for Muslims. And while the Pakistani supreme court overturned her conviction in 2010, Pakistanis continue to demonstrate against freeing her, insisting that the laws prohibiting blasphemy be strictly enforced.
The Torah, as understood by at least some interpreters, addresses the question by looking at a category of sin rather than an individual one. The daughters of Zelophehad approach Moses and argue that they should not be denied their father’s estate since their father died of his own sin rather than as part of the rebellious forces of Korah (Numbers 27:3). The Midrash (Sifre 133, 3) as well as the Talmud (Bava Batra 118b) explain that while Zelophehad personally sinned he did not cause others to sin. Inciting others to sin is so egregious a wrong that it would result in death, the forfeiture of assets and the eradication of one’s family name.
Zelophehad may have violated the Sabbath, in accordance with Rabbi Akiva’s view, or disobeyed God’s command, in accordance with Rabbi Simon’s view (Shabbat 96b). But these violations affected Zelophehad alone. The rebellion of Korah incited many beyond the initially small group of conspirators to challenge authority and this is far worse. Hence, the worst kind of sin imaginable is leading other to sin – a situation that ought to be scrupulously avoided.