At Bar- and Bat-Mitzvahs and weddings, it is usual for rabbis to pronounce the priestly blessing: “The Lord bless you and keep you; the Lord make His face shine upon you and be gracious to you; the Lord look favourably upon you and grant you peace” (Num. 6:24-26).
Everyone thinks this is a beautiful custom: but the Torah may have a different point of view. As the sidra informs us, it is the duty of kohanim to invoke these words of blessing… and rabbis aren’t (necessarily) kohanim.
To overcome the problem, some rabbis use an introductory formula, “May there be fulfilled in you the Scriptural verse, ‘The Lord bless you and keep you…'”, and they do not raise their hands in the same way that kohanim do when blessing the community.
But, one might ask, what is wrong with rabbis acting as kohanim? Is it really so wrong?
The answer is that Judaism knows of two kinds of leadership - leadership through heredity and through personal merit. Both have their place, but in the absence of a Temple there is little hereditary leadership and you can be a rabbinic or other leader irrespective of who your parents were.
Indeed the sages debate the question of who is higher in the sight of God, an unlearned high priest or a scholar who is of doubtful lineage, and decide in favour of the latter (Horayot 9:8).
The role of the rabbi is not a priestly one, as a liturgical officiant. Rabbis do sometimes conduct services, but not as rabbis but as ordinary laymen in whom the community has confidence. The real role of the rabbi is to be a teacher, guide and judge.
Does this mean he has power? Not usually. Ideally, what the rabbi has is influence, but that takes time to develop, and it can all be jeopardised by a rabbi who tries to bully his community. Why some rabbis become influential is because they deserve it.