I once read the following powerful story.
In the late 18th century, in Eastern Europe, there was a terrible conflict between the Chassidim and their opponents, the Misnagdim, who suspected the Chassidim in heresy and blasphemy. The chief opponent was the Vilna Gaon, the famed Rabbi Elijah (1720-1797), from the Lithuanian city Vilnius, who issued a ban (cherem) against Chassidim. He excommunicated them from the Jewish community. It was a terrible division which continued for decades.
The Misnagdim came to one of the greatest students of the Vilna Gaon, Rabbi Refael Hakohen Katz, the Rabbi of Hamburg and author of Toras Yekusiel (1722-1803), and asked him to sign the ban. He refused. They said: "But your own Rebbe, the Vilna Gaon, signed it, and your Rebbe is like an angel of G-d!"
This was his response:
There is a famous question on the story of the Akeida, the binding of Isaac, in Genesis. G-d instructs Abraham to bring up his son Isaac as an offering. Abraham complies. At the last moment, as he is about to slaughter Isaac, The Torah states: "And a heavenly angel of G-d called out to him, and said: Abraham! Abraham!... And he said: 'Do not stretch out your hand against the lad, nor do anything to him." At the last moment, Isaac is saved.
There is something strange about this story. The instruction to bring Isaac as an offering came directly from G-d. G-d Himself told Abraham to offer his son to Him. Why did the reverse stop-order come from an angel and not from G-d?
The answer, said Reb Refael, is this. If G-d wants to tell you not to touch a Jewish child, sending an angel will suffice. But if He wants you to "slaughter" another Jew, an angel can't suffice! G-d Himself needs to come and tell you to do it. If you are going to "slaughter" another Jew, make sure you hear it from G-d Himself. To let Isaac live, the instruction could be communicated via an angel. To let Isaac die, G-d needed to show up Himself.
"My Rebbe is an angel of G-d," Reb Refael said. "But I will not sign a ban against another Jew," even when an angel tells me to do so. To "slaughter" a Jew I need to hear it from G-d Himself.
[The source of the above story is Toras Yechiel by Rabbi Schlezinger Parshas Vayeira. Chut Hameshulah, a biography of the Chasam Sofer, page 27. In the latter the name of the student of the Vilna Gain is given as Reb Zalman of Volozhin, who was one of the most beloved students of the Vilna Gaon. There he also adds that when the Vilna Gaon heard this response, he himself abstained from any further action against the Chassidim! It is also interesting to note, that according to many sources, the famed Chafetz Chaim, Rabbi Yisroel Meir Kagan, who dedicated his life to increasing Jewish unity, and his works spread among all Jews, was a grandson of Reb Refael of Hamburg.]
Be Careful
Sometimes we get into fights with people over idealistic reasons. We "slaughter" people-with our words or actions-and we feel that we are acting on behalf of an angel. We feel angelic about our actions. Be wary, says the Torah! If you are going to cut someone off from your life, you want to hear it from G-d Himself. If not, let it go.