The Lord spoke to Moses saying, "Phinehas, son of Eleazar son of Aaron the priest, has turned back my wrath from the Israelites by displaying among them his passion for me, so that I did not wipe out the Israelite people in my passion."
The Hebrew word for "turned back," heshiv, comes from the same root as the word for repentance. T'shuvah is not simply feeling sorry, however. To make t'shuvah, one has to confess one's wrongdoing and go on to do everything in one's power to make the situation right again. It seems to me that is exactly what God does at the beginning of parshat Pinchas (Numbers 25:10). God makes t'shuvah.
What does God confess? A few verses earlier, in response to the Jews' idol-worship, the Torah quotes God as saying, "Take all the ringleaders and have them publicly impaled before the Lord, so that the Lord's wrath may turn away from Israel." As harsh as this extremely unusual sentence may be, it is a judicial sentence, a punishment for a crime. Perhaps God could carry it out and go no further--but human beings cannot. As I recounted on July 30, Pinchas takes out his spear and stabs Zimri and Cozbi on the spot. The plague of disease called "the Lord's wrath" threatens to turn into a plague of vigilante justice.
As I interpret it, God is shaken. Throughout the Torah, human beings have the capacity to surprise the divine being. A God of justice cannot conceive that human beings could turn justice into slaughter until Pinchas' action rudely brings that fact to God's attention. "Here," says Pinchas' spear," is what happens when you command human beings to take life and death into their own hands. Is this really what you have in mind?"
Pinchas' action turns God's action back on itself. It reflects the consequences of drastic justice in the mirror of finite and fallible human beings. Finally, it turns back God's command itself. B'kino et kinati, "by being zealous with My zealousness," Pinchas has forced God to repent of God's harsh judgment and to make things right by ending the extermination then and there.
God needed Pinchas to show what untrammeled zealotry can do to human beings. Being human, we should already know that for ourselves. That is the advantage of being human--if we let it.