Why will the people no longer say, ”The fathers have eaten sour grapes, and the children’s teeth are set on edge”?

When the Lord returns his people to the land they will no longer use the proverb that says, The fathers have eaten sour grapes, and the children’s teeth are set on edge. Ezekiel has a similar message (Ezekiel 18:1–4), where the Lord rebukes his people for using the same proverb and also promises that the day will come when they will no longer use it. In the proverb eating sour grapes would refer to someone sinning and having their teeth set on edge refers to the consequences of their sin. The proverb therefore speaks of a situation where people are paying for the sins of their forefathers. It seems that this is a complaint made by the generation in Judah that faced the Babylonian invasion. They were blind to their own unfaithfulness and felt that they were paying the price for the unfaithfulness of those who came before them. There is a sense in which this complaint could have been seen as valid in Jeremiah's day. For generations the Lord had patiently restrained his judgment against the unfaithfulness of his people but now his judgment would come in all its fullness against the people of Jeremiah’s day. Of course, the Lord’s judgment is coming against their own unfaithfulness as well. However, when the Lord returns his people from exile they will no longer be blind to their own failings. They will no longer use the proverb and instead everyone shall die for his own sin. Each man who eats sour grapes, his teeth shall be set on edge. Every person will be responsible for his own sin. This is not a new understanding of personal responsibility. The Lord clearly taught this people this principle when he renewed his covenant with them (Deuteronomy 24:16). What will be new among his restored people is a deep awareness of personal responsibility before the Lord. However, simply being aware of personal responsibility does not solve the problem of the unfaithfulness that has been in the hearts of his people from the beginning.

This oracle (Jeremiah 31:27–30) does also highlight the relationship between personal and corporate sin in Israel. In the terms of the covenant, the Lord made it very clear that every individual was to love the Lord with their whole heart, soul and strength (Deuteronomy 6:4–5). Every person was responsible for their own relationship with the Lord. But he also made it clear that the whole nation would experience the consequences of covenant failure. It is clear that what is needed for the nation to successfully return from exile and be re-established in the land is both a personal and corporate commitment to the Lord. How then can the Lord return his people from exile if unfaithfulness still lurks in their hearts? That crucial question will be answered in the passage that follows in Jeremiah 31:31–34.