The Subtle Rebuke
The Book of Devarim-Deuteronomy begins with Moses’ words of rebuke to the Jewish people:
These are the words which Moses spoke to all of Israel on the east bank of the Jordan; in the wilderness, in the Plains (of Moav) at the Red Sea, between Paran and Tofel and Lavan, and Chatzeiros, and Di-Zahav.”
According to Rashi his rebuke is couched and camouflaged in the opening words of the book.
Rashi explains that these references allude to the sins the people committed in the desert. “To preserve their dignity, he did not criticize the Jewish people outright. Instead he mentioned the places where they had sinned.”
The Rebbe (Sichos Kodesh, Devarim 5725-cited in the Gutnick edition) draws an obvious lesson from Moses’ behavior. Even if we have to rebuke someone who has sinned egregiously (as did the Jewish people in the desert) we should do so softly and subtly, while at the same time drawing the person close with warmth and love.
Why did Moses Change His Approach?
Alshich (a 16th century Biblical commentator) raises the obvious question:
As we read further, Moses seems to drop his subtlety and reprimand them openly. For example (in verses 26-27) Moses says to them:
“You did not want to go up, and you rebelled against the word of G‑d, your G‑d. You spoke slanderously in your tents…”
Why did Moses change his modus operandi, from subtle hints to unmitigated, harsh criticism?
Isaiah Punished for Harsh Words!
The work Avnei Eliyahu answers this question by referring to a similar enigmatic Talmudic comment on the words of the prophet Isaiah. Isaiah (6:5) records his critical opinion of the Jewish people:
“Then I said, ’woe is me, for I am doomed. For I am a man of impure lips and I dwell among a people of impure lips…’”
In response to his remark, the Biblical text describes how he was punished for his intemperance:
“One of His seraphim flew to me and in his hand was a coal. He touched it to my mouth and said, Behold, this has touched your lips; your iniquity has gone away and your sin shall be atoned for.”
The Talmud (Yevamos 49b) goes as far as saying that for his biting criticism of the Jewish people - that he lives among a nation of impure lips - Isaiah was murdered by his own grandson, King Menashe!
The work Yaros Devash (by Rabbi Yonoson Eibishutz, a famous 18th century rabbi) raises a powerful question:
The very same prophet had uttered far more critical words of the Jewish people in the first five chapters of Isaiah, many of them are recorded in this week’s haftorah. Why did the relatively mild statement that the lips of the Jewish people (as well as his own) were impure go too far? Why did that elicit such a powerful punitive response from the angel and then having to suffer murder at the hands of his own flesh and blood?
Channeling and Composing
Avnei Eliyahu answers that Isaiah’s original criticism was not his own. As a prophet he was merely channeling G‑d’s words. He was not in control of what he said. His solemn responsibility as a prophet was to faithfully transmit G‑d’s message. He could not water it down.
By contrast, when he referred to the Jewish people as having impure lips that was stating his own assessment and criticism. For volunteering that negative judgment he was punished.
The lesson here is that even when one has to criticize another for his or her improper behavior it should not be from our own heart; we should just dispassionately communicate the words of the Torah. In our hearts we should feel love and compassion for the sinner but fulfill our obligation to rebuke the sinner, if necessary, with G‑d’s words, not our own.
Moses’ Change of Approach
This explains why Moses’ initial rebuke of the people relied on hints rather than outright criticism. In the opening verse of Deuteronomy, Moses expresses his own sentiments, as the Torah writes: “These are the words which Moses spoke to all of Israel.” Because these were his own words he wanted them to be as gentle and indirect as possible. He therefore just mentioned the locations where the people sinned.
However, later when he recounted what G‑d instructed him to tell the people he was merely a conduit; he could not editorialize or alter the message. 
On a deeper level, Avnei Eliyahu observes that Isaiah’s initial rebuke was followed by the verse:
“If your sins are like scarlet they will become white as snow, if they have become red as crimson they will become white as wool.”
The underlying meaning of this verse is that not only will G‑d forgive us when we repent, but if we repent out of love our sins themselves will be transformed into merits, as the Talmud (Yoma 86b) states.
A story is told of Rabbi Levi Yitzchak of Berditchev who was famous for the positive way he viewed everyone. He once summoned the biggest sinner in town and confessed that he was jealous. The sinner thought the rabbi was poking fun at him. The rabbi explained that if he did Teshuvah (repented and returned) then all of his sins would be converted into Mitzvos-virtues. Rabbi Levi Yitzchak concluded, “I can never observe as many Mitzvos and accumulate as many merits as you can just by virtue of the number of sins that will automatically metamorphose into Mitzvos!”
Thus, in that vein Isaiah enumerated the many sins of the people, knowing that they would ultimately be converted into merits. The more sins he mentioned the more merits that would accrue to the people.
Similarly, when Moses wanted to rebuke the Jewish people he was initially concerned that to speak openly of their transgressions would cause them shame. Moses’ respect for their honor was born out of his incredible love for them. His rebuke was thus motivated by love for his people and his G‑d.
Since these words of reproof emanated from Moses’ loving heart they certainly elicited a reciprocal response. This is in line with an ancient saying that: “Words that emanate from the heart enter the heart and have their desired effect.”  The Jewish people, too, were filled with Moses’ love and they therefore repented out of love for him and G‑d.
Once that happened, Moses was no longer apprehensive of directly mentioning their sins, because all of their sins were actually now transformed and converted into Mitzvos. Hence, the more sins Moses enumerated, the more merits the people accumulated, which resulted in an enhancement of their spiritual status, as the Talmud declares, “The place where a Ba’al Teshuvah stands, a perfect tzadik cannot stand.” This has been interpreted to refer specifically to the one who does Teshuvah out of love.
Three Reasons for our Eligibility for Redemption
One of the questions many people have about our eligibility and worthiness for the Final Redemption is how could it be that we, with all of our shortcomings, will be the ones deemed eligible for Redemption? The question is even stronger considering all of the preceding generations of righteous people that could not bring Moshiach. How can we?
There are generally two responses to this question, but in light of the above discussion we can advance a third rationale.
The first approach is that we have the benefit of the cumulative good of all past generations. Evil disappears when sinners either repent or are punished. The forces of goodness and holiness, by contrast, are permanent. Each Mitzvah a person performs is added on to the existing cumulative good. We are like a child standing on the shoulders of a giant who can therefore see further. We have all of what our forebears accomplished plus the little extra that we do.
The second approach is that, on the contrary, there is something unique about our generation. We live in a world where spirituality is so concealed; where G‑d’s presence is so deeply challenged. We were exposed to the challenge of utter darkness in the 20th Century, during the Holocaust and the reign of terror under Communist tyranny. The challenge of bodily persecution was followed with the spiritual challenge of assimilation. Thanks to G‑d, we may live in a period of tremendous affluence but it comes with the threat of losing our identities as Jews. The challenge of enticement, assimilation and submission to popular culture, with all of its blandishments, is so very great. And yet, despite all of the above, we, as a people, have remained loyal and faithful to G‑d and His Torah. We are truly an extraordinary people, well deserving of Moshiach and Redemption.
However, in light of the above discussion a third argument can be advanced. Whereas in the past, people who sinned and repented did it out of fear of punishment, retribution, loss of reputation, etc., today’s generation does it out of love. Hundreds and thousands of young and old have made a 180 degree turn in their lives because they fell in love with G‑d, Torah and Mitzvos. Our generation is the generation of Teshuvah motivated by love and we therefore have converted not only our own past misdeeds, but we have converted the sins of all previous generations into virtue.
Not only do we have the cumulative good of the past in our arsenal, but the past evil converted into good energy is also at our disposal. With that immense power we will certainly overwhelm the world of darkness, which we call Galus-exile, and bring about the coming of Moshiach and the Final Redemption, imminently
This idea is especially relevant this year when Tisha B’Av occurs on a Shabbos and the fast must be postponed. When Tisha B’Av occurs on a Shabbos this transformation of the negative into good is clearly in view. We take the day with the most negative energy and transform it into a day of delight and joy.
In this spirit may we see the total postponement and abolition of the fast day and instead rejoice in the greatest and most joyous Holiday—the Festival of Tisha B’Av with the imminent revelation of Moshiach!