In the Zohar HaKodosh, there is an alternate girsa (textual variant) in Parshas VaYechi from daf 211b-216a, which according to the Masok Midvash is not properly Zohar, though it is quite interesting nonetheless. It states on 215b, that in relation to a posuk in Yeshaya that says “And you say in your heart, ‘who birthed for me these?'” that this refers to geirim. The one speaking is Klal Yisroel L’Satoh, the lower form of Yisroel, meaning basically Yisroel in the manifested world. The Shechinah asks these foreign people gathered together with Yisroel L’Satoh, “Who are all these,” and they are observed to not possess the impurity of complete foreigners, so “these,” meaning the other people gathered with Klal Yisroel, say “We are all your children.” After this, those who are meant to be part of Klal Yisroel are gathered in and “cut into” the covenant and are considered exactly like born members of Klal Yisroel, which is part of an explanation according to Sod of the statement in the gemoro that geirim are tough for Yisroel like a skin problem. The conclusion of this is that geirim are considered to be such a part of Klal Yisroel that they are literally considered buried in the flesh, to the degree that they will also be returned to Eretz Yisroel with all the born Jews when Moshiach comes.
A further explanation continuing throughout the daf and a touch into the next one explains that the entirety of the adornment of Klal Yisroel, and what makes Klal Yisroel and a Jew a Jew is the Torah itself. The most important thing for a Jew, the only thing that gives a Jew anything special whatsoever, is learning Torah and fulfilling mitzvos. At first glance, this may seem to contradict what we learn from the Baal HaTanya, who states that every Jewish soul naturally has a special piece of Hashem within them, which makes a Jewish soul more special. The truth of the matter is, if we contemplate these two views together, we can come to a measured conclusion. While a Yid has a special neshomo, the only way this actually helps with anything is if that neshomo is fortified with Torah. Without Torah, the neshomo remains trapped in Klippah and darkness. We could perhaps even say that the specialness of the Jewish soul, the חלק אלוקה ממעל ממש really is a hint to the Torah that their soul has acquired and learned in this world, as it says אורייתא וקודשא בריך הוא כולא חד, the Torah and Hashem are totally one: so we can say that the special piece of the Highest Divinity within the נפש היהודי is directly related to the Torah they learn and their involvement with the mitzvos. This is not to say that if someone is not a huge Talmid Chochom that they are lacking this, rather that the complete holiness of a Jew depends on their involvement with Torah through the study they earnestly do, like it says in the gemoro in Brochos, it doesn’t matter if you learn much or a little, so long as your heart is directed towards Hashem; along with fulfilling the mitzvos of the Torah with simcha and satisfaction of the heart.