How does one decide?
Below is a wonderful Chabad teaching that sheds light on this important topic. It was produced for Chanukah however the teaching goes far beyond the holiday. The lighting of the candles, the oil, etc. is used as a metaphor for these two approaches. Both are presented as being correct and having merit.
During the first century BCE two great rabbis debated many topics about what it means to be Jewish and how Halacha (Jewish law) should be applied to daily life. This debate is again raging between Orthodox and Non-Orthodox, between Chassidus and the Misnagdim. Is Othodoxy the "real" practice of Judaism? Do the non-Orthodox breath needed new life into modern Judaism? The debates continue.
In general terms Rabbi Hillel advocated for a "big tent" approach that sought to include all Jews and welcome others while Rabbi Shammai favored a "small tent" approach in which only those who were genuinely observant would be included. To this degree the argument is between Judaism being a small community of tzadikim (truly righteous people) or a larger community where all of Israel is included regardless of their level of observance. Both approaches have positives and negatives.
Overall the big tent approach of Rabbi Hillel was determined to be the most applicable to the realities of Jewish strengths and weaknesses. The negative to this perspective is that the importance of holiness and observance is sometimes minimized in favor of inclusiveness.
In today's world, especially in the diaspora (i.e. among the Jews living outside of Israel), this approach has arguably resulted in the growth of a Judaism that has become so assimilated with the various non-Torah based cultures that the uniqueness and purpose of the Covenant has been weakened and in some cases abandoned completely. This debate is critcal today as Rabbinic Judaism has almost become series of contrary rival sects.
Can a Jew be too observant? Can one not be observant enough? What does it even mean to be observant today? Must we in the 21st century conform to rules established in the pre-modern era that seemingly no longer apply? Is not Judaism a living organism that must adapt and conform with the times if it is to survive into the future? Is it possible to go too far with this, in either direction? Where should we set our boundaries and "hedges"? These are the essential debates between the Orthodox and non-Orthodox movements. Between Chasidus and the Misnagdim there are other divisions. This is complicated by the fact that many modern Hassids have seemingly abandoned many of the reforms of the Baal Shem Tov. Many today are indistinguishable from the Misnagdim. The more things change the more they stay the same.
Once Mashiach ben David comes Rabbi Shammai's approach will certainly adopted because then we will all know the truth. Then there will be a righteous King on the Throne of David in Jerusalem. Then the tzadikim will teach openly and then all people will partake in the truth of Torah. Then the righteous Noahidim (people of the nations) will come to Jerusalem's Holy Third Temple and make sacrifices to HaShem knowing His Will and the role of the Jews as His anointed priesthood to the nations (Exodus 19:6). Then they will learn and make peace with the Jewish people. Then... Oy! Such a time it will be!
Until the Messiah comes however we must not allow the perfect (Shammai) to defeat the good (Hillel). In other words, as Rebbe Nachman says, "a little is better than none" for now. So don't stress over observing the minutia of laws and traditions. Such forced pseudo holiness can actually move one away from HaShem because such a person inevitably decides, "I just can't do it! I don't know the proper rites and words, the rabbis dan't even agree so how am I supposed to do this!"
BUT, don't worry! Be happy! Just keep growing, learning and gradually increasing your emunah (active faith and trust). Your service to HaShem with the intention (kavanah) to please Him is enough! "Torah was given to fallible humans, not to the angels" as Rebbe Nachman also teaches us. HaShem knows your heart. Study Torah, pray and be joyful, and do what you are able to do with the understanding you currently have. Your understanding, your observance, and you joy will gradually increase.
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