Devarim 27:26
Cursed be he who will not uphold the terms of this Teaching and observe them. And all the people shall say, Amen.
Rashi
Here he [Moses] included the entire Torah under a curse and they took it upon them pledging themselves by an execration and an oath.
Sforno
who neither observes nor admits that they are all worth observing, but, who in his arrogance, considers some commandment or commandment of the Torah not worth his while observing. In the Talmud such a person is considered a “heretic because he rejects a single one of God’s commandments.”
Rabbi Adin Steinsaltz
In this parasha, as in other places in the Torah, many harsh things are described. Why are so many curses necessary? Why is it necessary to threaten the people with such dire consequences for disobedience? Why can’t the Torah always speak pleasantly?
…
in our world it is hard to be a Jew. … we live among human beings and not in a sheltered environment
In the past several weeks, we’ve read from Rabbi Steinsaltz that the Torah has to be taken as a whole and should be not rewritten to suit simple principles that we find easier to accept. Here he says that the Torah includes difficult thought and language because life is not always easy. We need to recognize and be prepared for ugly realities.
Devarim 29:1-3
Moses summoned all Israel and said to them: You have seen all that the LORD did before your very eyes in the land of Egypt, to Pharaoh and to all his courtiers and to his whole country: the wondrous feats that you saw with your own eyes, those prodigious signs and marvels. Yet to this day the LORD has not given you a mind to understand or eyes to see or ears to hear.
Rabbi Yehudah Leib
But now that the whole Torah was completed and all their own behavior had been made into Torah, there was something fixed for all generations.
This is the meaning here of “this day.” … Torah had been formed out of all their own actions. This was the great merit of Israel in accepting Torah. Torah itself is completely beyond measure, “hidden from the eyes of all who live” (Job 28:21). But Israel deserved to “garb” that Torah; from all their deeds a cloak was made for the light of Torah, in the teachings and commandments of that Torah that is before us. Understand this.
Rabbi Arthur Green [commentary on this section of Sefat Emet]
[this] provides a key opening for a radical rethinking of revelation and the relationship between revelation and commandment. The Torah God reveals at Sinai is one of pure divine light, a vision of infinite love and giving that as yet has no particular form. Israel, because their hearts are open to receive God’s light, come to stamp the revelation with the particular forms — ethics, rituals, beliefs, taboos, and all the rest — of their own culture. For later generations these come to be associated with the revelation and are accepted as God’s commandments.
…
Torah in its deepest essence is nothing but God; what God gives at Sinai is God’s own self, but now transposed into the medium of words and language, in order that humans can receive it. The specific details of Torah … are derived from the actions and life-experiences of Israel. Through these Israel are “made into Torah.” Torah is then at once a thoroughly divine and thoroughly human product.
photo: By Jukka Wallin – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=75708653