(1) Gerim are not the children of Yisrael - they came from different nations, and while they are certainly deserving of great praise for leaving their old ways and coming under the wings of the Shechinah, they nevertheless are not originally from the Bnei Yisrael.
(2) There is an interesting Tosfos in Bava Basra 81a DH Lim'uti which cites a dispute whether a Ger can say "Avoseinu" - Our forefathers - for instance in the Shemoneh Esreh. Some say that he cannot but others say he may, because Bereishis 17:5 states that Hash-m said to Avraham Avinu "I have placed you as the father to a multitude of nations". The Halachah follows the latter opinion. However, it is possible to suggest that Avraham is called the father of all the nations, but Yitzcahk and Yaakov (i.e. Yisrael) are not.
(3) We do find other instances in Halachah where, while Gerim are on a very high level, they are nevertheless (i.e. generally speaking only in the first generation) not quite equivalent to born Jews. See, for instance, Devarim 23:3, "A Mamzer may not marry into the congregation of Hash-m" which Rashi explains to mean that he may not marry a Yisraelis. Kidushin 72b-73a, and the Poskim there, state that he may marry a Giyores, because the congregation of Gerim is not called "Kahal Hash-m."
(4) See the Mishnah below Sotah 41a which relates the incident involving King Agripas. He read in the Torah that the King must not be a "stranger", and started crying. They said to him "Do not worry, Agripas, - you are our brother". Rashi explains that this is because his mother was Jewish. This implies that if both parents would have been Nochrim and he a full Ger, he certainly would not have been called "Our brother". See Tosfos 41b DH Oso who disagrees with Rashi and maintains that the King is only appointed if both parents are Jewish.
(5) In fact, there are opinions that one does not give the bitter waters to a Giyores to drink (see Mishnayos Edayus 5:6, according to Akavyah ben Mahalel). Rashi Berachos 19a DH Lo writes that this is because the Torah states "Bnei Yisrael" which excludes the wife of a Ger (i.e. the Hava Amina in our Gemara). However the Halachah does not follow Akavya. (See also Mishnehh le'Melech to the Rambam Hilchos Sotah 2:6 who writes at length on this.)
(6) See Yerushalmi Sotah 2:5 that indeed states that if a Yisrael marries a Giyores one does not give the wife to drink because the Pasuk says "Bnei Yisrael" but not a Giyores. However, the Rambam (Sotah 2:6) does not Pasken like the Yerushalmi but instead Paskens that a Giyores or the wife of a Ger have exactly the same Din as other ladies, and must drink the waters.
(7) In summary, one sees from the above that there are opinions that the Parshah of Sotah does not apply to Gerim, and the reason is because they are not born “Bnei Yisrael.”
KOL TUV Dovid Bloom (dafyomi.co.il)
