"… So that they may be one, just as we are."
The Torah leaves with much to discuss. It may be that the Father in His great wisdom designed It that way that we may spend our time in studying it. We may feel like we forever learn without coming to the complete understanding but we are not talking a mathematical formula here, we are talking about the elements through which the worlds were created by the hand of the Almighty. As my wife recently told her ninety-nine year-old aunt who is just now (as she is facing imminent death) yielding to the idea that after all, there is a God, "Show me a man who can understand God, and I'll show you a worm who can understand man!" The claim of understanding the Word to the point of formalizing doctrine in established statements implies that one completely understands the fullness of the Torah, but can the Word of God fit in the human brain? What arrogance people have! This is why the Talmud which is the Jewish commentary to the Scriptures is a discussion, not a document establishing doctrine.
The Torah teaches us that there is one commandment for the Israelite-born, and for the 'ger', the stranger in the Land (Numbers 15:14-15). In this manner God established how He wants to be acknowledged and worshipped by all the people in the world; it is not up to us to decide how to honor Him. In this day and age people go away from worshipping in the spirit and truth of Torah, and establish their own righteousness; but spirituality outside of the parameters of Torah leads to heresy and idolatry.
The Torah teaches distinction between person and person even within the Israelite nation, so while provoking homoethnicity, the fact that the same rituals are to be observed by both Israelites and non-Israelites doesn't erase distinctions. What Paul coined as the 'one new man' is as 'one' as a man and a woman are one flesh (Genesis 2:24) while remaining two distinct genders and personalities (Ephesians 2:15). The same principle applies to Yeshua and the Father who while united, remain two distinct personality even in power and knowledge (John 14:28; Mark 13:32).
Come to think of it, while being under the Torah may provoke ethnic coalescence, the beauty of it remains in the fact that we are all unique individuals. Unity is not the absence of diversity, but the working together in spite of, and within our diversity. Paul explained this principle of Israelite/gentile unity in diversity, but still called it a 'mystery', so maybe we should also just leave the issue rest there and be happy with a 'mystery' (Ephesians 3:1-7).
Yeshua coined it very well though; peering into the future of the international ministry of the disciples He said, The glory which you have given to me, I have given to them; so that they may be one, just as we are one. I united with them and you with me, so that they may be completely one, and the world thus realize that you sent me, and that you have loved them just as you have loved me (John 17:22-23).