Left behind after final redemption

Question

This question is based on the Ha Yom Yom sefer which is well know to the Chabad school of thought adherents.

We are taught that Moshiach will gather the Jewish people from all corners of the earth and return them to the Promised Land.

We also learn in the Ha Yom Yom , Sivan 18, ...inspire the other to teshuva (return), so that he will not fall out - G‑d forbid - of the community of Israel who will shortly be privileged, with G‑d's help, to experience complete redemption.

So who is this person who might fall out - G‑d forbid - of the community of Israel ?

I thought every one will be gathered when Moshiach comes; without anyone being left behind.

Answer 1

The Rebbe often insisted, based on numerous Maamarei Chazal, that every Jew will ultimately repent (or more accurately, return to their true essence) and merit the redemption. (Or as Avraham Fried phrased it, No Jew Will Be Left Behind.) Indeed it's one of the central distinctions between the redemption from Egypt and the coming redemption. In that vein, the Rebbe reads the rebuke of the Haggadah to the Wicked Son, "if you were there you would not have been redeemed" as implying that in the future redemption, he will be redeemed.

I don't know if the Rebbe directly addressed this Hayom Yom, but it could hardly have escaped his notice, considering he compiled it. I think it needs to be read as a hypothetical alternative, as opposed to an actual possibility. Sort of like how "don't touch that power line if you value your life" should be understood to be ruling it out as a reasonable possibility. This can also be inferred from the continuation of the original letter excerpted in Hayom Yom:

כי ח"ו וח"ו שום איש ואשה בישראל לא יחפוץ להיות כמו אלו שמתו בשלשת ימי האפלה במצרים לפי שלא האמינו בגאולה, ובודאי כי כל החי בישראל, בין איש ובין אשה מאמין בביאת גואל צדק, לכן כאשר יעוררו אותם יתעוררו בתשובה

Answer 2

In the editions with explanatory footnotes, it emphasizes for the 18th of Sivan that this was relevant to the time of "the Heels of Moshiach".

That implies that after that time period, meaning like today, the possibility for variations in the final redemption are past. That HaYom Yom was published in 5703-4, prior to the bombing of Hiroshima and Nagasaki, which signaled a different tekufah in regard to Moshiach and the final redemption.

It also says that the idea relates to the concept of Teshuvah like explained in Mishneh Torah Hilchot Teshuvah, meaning that because all Israel are a part of the whole, and the judgement for meriting redemption is on the whole, when we reach a simple majority of merit in regard to the individuals 51%, those who may have been judged as not meriting redemption are converted to merit like Rambam explains.

So the focus was on attaining the simple majority of individuals (כל אחד מישראל) to merit redemption for the whole nation, meaning כלל ישראל. No one gets left out.

It also is focusing on the concept of how quickly everyone will be redeemed. That at that time, it was possible for the redemption to be faster or slower, even in a matter of only a few days.