The cultural gap between then and now is just too great to ever go back. And even if we could transcend the differences, we would still be seeking a world that never really existed. Even in the days immediately after God's mighty acts in Yeshua, there was plenty for believers to fight about. Still, certain rock-solid points of identity modeled and taught by the people who gave us Scripture can and must inform our sense of who we are. The self-understanding of the Apostles as both Jews and followers of Jesus is a case in point.
History moves on, but identity-shaping paradigms remain strong and steady through the centuries.
So, just as the constitution of the United States, a 200 year old human document, circumscribes the foundation identity of the modern American citizen, so the 2,000 year old New Testament confirms the legitimacy of modern Messianic Jewish identity. And for Jews, that identity is first and foremost, Jewish. History has marched on. This means that Messianic Judaism must be defined in terms of what Jewish life has come to look like since the days of Yeshua. Messianic Judaism correctly reflects the collective experience of the entire Jewish people as our culture has developed over the centuries.