If a gentile has been called upon to give the blessing before a wedding meal, with part of the wedding party being Jewish, would there be any problem with including a standard bracha at the end of the prayer, ("baruch atah adonai elokeinu melech haolam" followed by the bracha for wine), where the goal is to make the point that there is one God for all, and to welcome the Jewish participants?
Maimonides states that a person is not allowed to answer Amen if a nonJew makes a blessing and it is not considered a valid blessing. In fact, given that the groom is attempting to "marry" a nonJewish woman, one would probably not be allowed to answer Amen if he (or another Jew) said the blessing.
Hilchos Brachos chapter 1 law 13
13 Whenever a person hears a Jew recite a blessing, he is obligated to respond Amen, although a) he did not hear the blessing in its entirety, b) he was not obligated to recite that blessing himself.
One should not respond Amen if the person reciting the blessing is a gentile, an apostate, a Samaritan, a child in the midst of study, or an adult who altered the text of the blessing.
The use of the Amen serves to state that the blessing being made is appropriate and valid. The Rambam states in the laws of oaths that a person can be considered to have sworn to the truth of the oath being stated (by another) by answering Amen. Similarly we see in the Torah that a sotah becomes subject to the curse by answering Amen to the oath that a priest reads.
Thus, when a person answers Amen to a blessing he is stating that this is a valid blessing and he is including himself in that blessing (such as now being able to drink the wine or eat the food). If a person is not allowed to answer Amen to a blessing, then the implication would be that it was not a proper bracha.
The concept of a bracha actually has two components to it as it relates to the halachic system. On the one hand, a bracha is a halachic action, a religious performance like any other. The reason a person recites a bracha prior to eating food, for example, is that benefiting from this world requires a matir, so to speak; thus, the bracha is functioning as a halachic performance. As such, a person must be able to relate to this very system in order to recite the bracha. He must be a gavra hamechavein, possessing the inherent ability to have intent prior to engaging in a halachic performance. Based on this reasoning, one would never answer “Amen” to the bracha of a non-Jew, as he is essentially unable to engage in any Jewish religious performance.
There is another aspect to bracha that makes it unique, which will aid us in understanding how one could answer “Amen”. The text of a bracha is a statement of objective reality. Within the bracha, a person expresses the fact that God is Blessed, King of the Universe, and relates this idea to the performance at hand, such as referencing God as the “boreh pri ha’adama”. And as we know, the response of “Amen” is in fact an acceptance of this very truth. The Rambam notes that we answer “Amen” even if we are not ourselves obligated in said bracha, indicating that it reflects our acknowledgment of the truth contained in this expression. If this is the case, then the intent of the individual becomes of secondary import. It is true the non-Jew does by definition not have the right intent when making the bracha. However, the cheftzah of bracha is able to emerge regardless, as it stands on its own as a declaration of truth. Therefore, according to this opinion, one should respond “Amen” when (on the off chance) he hears a non-Jew recite the bracha.
In terms of practical pesak, both positions can be found throughout the works of Rishonim and Acharonim. The Tur (OC 215) cites both opinions (his father, the Rosh, following the second line of reasoning). The Shulchan Aruch (ibid 2) only cites the issue as it relates to a kusi; however, he writes in another place (ibid, Beis Yosef) that the kusi is equated to the non-Jew, and therefore we would not answer “Amen” to his bracha. The Rema, however, writes explicitly that one should answer “Amen” to the bracha of the non-Jew.
A more contentious issue emerges in the case of answering “Amen” to the bracha of a kofer/apikoris, an individual who denies a fundamental yesod of Judaism, such as Torah from Sinai, or possesses a distorted idea of God.
He cites Rav Moshe Feinstein as stating that the words of a kofer are actually worse than the blessing recited by a non-Jew and may not be answered at all. This would apply if the (Jewish) groom were asked to recite the blessing.
R Moshe Feinstein (Igros Moshe OC 2:50, as well as in other teshuvos) expands on this issue, reinforcing that one should not answer “Amen” to a bracha recited by a kofer. He writes, in referring to Conservative/Reform rabbis, that since they are denying God and his Torah, the enunciation of the name of God by them is simply words (devarim be’alma) without any intent towards God. Therefore, it does not even rise to the level of an actual bracha, lacking in shem and malchus.
You should also note that if the groom says the normal statement made at a Jewish wedding (or someone says it for him)
Behold you are sanctified to me by the laws of Moses and Israel
he is actually stating explicitly that this is not a valid wedding.
Another problem would be if the food (or the wine in this case) is not kosher. There is a dispute between the Rambam (Brachot 1,19) and the Rosh. The Shulchan Aruch (Orach Haim 196,1) rules in line with the Rambam, that one does not say a bracha before or after eating non-kosher food. One should note that the dispute involves whether a Jew (for whom it is a sin) may or may not make a blessing on it.
Note that with wine, this applies even though it was not "used as a libation for idol worship" because the laws of libation also apply (by rabbinical decree) to any non-kosher wine.
Hilchos Brachos chapter 1 law 19
19 When a person eats a forbidden food - whether consciously or inadvertently - he should not recite a blessing beforehand or afterward.
What is implied? If one eats tevel - even food that is classified as tevel by Rabbinical decree, the first tithe from which terumah was not separated, or the second tithe or sanctified foods that were not redeemed in the proper manner, one should not recite a blessing. Needless to say, this applies if one ate meat from an animal that was not ritually slaughtered or was trefah or if one drank wine used as a libation for idol worship.
There is a discussion as to the reason behind this dispute which centers on whether the essential meaning of the blessing is centered on whether this is a blessing on a sin (and may even be blasphemous) or that it is valid (after the fact) because there was enjoyment of Hashem's bounty. It is possible that a non-Jew (for whom the food is permitted) would be able to make the blessing, although Jews should not answer Amen.
The Rambam writes "When a person eats a forbidden food - whether bemaizid (intentionally) or beshogeg (inadvertently) - he should not recite a blessing beforehand or afterward" (Brachot 1,19). This is also found in the Talmud Yerushalmi, where it explains that such a blessing would be "na'atz Hashem", as in Tehillim 10,3 which can be read as "the one who blesses and blasphemes Hashem". What a chutzpah to say a bracha on sinful eating!
However, both the Ra'avad and the Rosh rule that a blessing must be said before and after eating non-kosher food. The Mishna merely rules that a non-kosher meal is not considered as important enough to require a zimun on it – but in the words of the Ra'avad, "why shouldn't he say a bracha before and after eating, since he enjoyed the food?"