It is not quite correct to say that a Nochri cannot bring Shelamim. Rebbi Yosei maintains that a Nochri may bring a Shelamim, proving his point from Vayikra 22 where it says that "all of their Nedarim and Nedavos" are acceptable. This view is also brought in Shekalim 1:5.

However, Rebbi Akiva and Rebbi Shimon disagree and maintain that every sacrifice of Nochrim is an Olah even when he donates a Shelamim. The Rambam (Hilchos Ma'aseh Korbanos 3:3) records this view and adds the reasoning, "since a Nochri's intention is for heaven," meaning that when he donates sacrifices he intends them to be burnt offerings and not to be eaten. This could be because in general the concept of an offering in pagan culture was not to be eaten but rather to burn them.

Another possible reasoning is based on the Midrash (Tanchuma Tzav 5) which states that the Shelamim is in the plural since it makes Shalom between Yisrael, the Kohanim, and Hash-m, as each receives some part of the Korban. Thus, this is a unique and intimate sacrifice designed to make peace between Hash-m and Yisrael and this peace does not concern Nochrim.

The Midrash also describes how the Nochrim claimed to Bil'am that they deserve to sacrifice as well, and he responded that they did not accept the Torah ("Hash-m Oz l'Amo Yiten..."), so they are not deserving of the Korbanos which make peace between Hash-m and Yisrael ("... Hash-m Yevarech Es Amo ba'Shalom").

Yoel Domb