Once we’re on the topic of Rav Shach zt”l, Rav Shach zt”l was rather clear in his denunciation of Lubavitch and called it avoda zara. In return for his kind-hearted efforts to save a large portion of klal yisroel from eveira, he was called “Shach” and “mibnei banav shel Haman limdu torah bebnei brak”. He was not denouncing Lubavitchers, which is a big difference
several ponts to consider (i dont think any of us can say who is right or wrong)
One was the Rebbe’s innovation of learning Rambam everyday to finish it in 1 years or 3 years. R. Shach mocked it saying that people already knew of the Rambam before the Rebbe came around, and he said that no one should follow the Rebbe’s Rambam learning cycle. (He supported daf yomi, and never rejected it saying that people knew of the gemoro before R. Shapiro). He gave two reasons: that people will pasken from the Rambam and it will disrupt seder. Neither of these points seem to be valid, as people who learn Rambam know that we don’t always pasken according to the Rambam; and the Rebbe was very adamant that chitas and Rambam should not be learned during seder.
Another thing of contention was whether you can give land of Eretz Yisroel away. The Rebbe was very against giving away land, while R. Shach supported giving away land for “peace”.
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The Rebbe got very upset when R. Shach spoke really sharply against non religious Jews and kibbutznikim, saying that they forfeited their right to be called Jews. The Rebbe said that “every Jew is part of God” and that “anyone who berates any Jew is touching the apple of God’s eye. (The Rebbe was always careful to only speak of other Jews favourably, similar to the derech of the berditchiver.)
as we see slowly that more and more non lubavtichers relize this (E.g. aish hatora)
and other kiruv