Before a person can confess his sin, he must first know his sin. That is why Jeremiah says, “Let us examine and test our ways.” The people should ask themselves what direction their life has been going in, what they have done and thought and said. How their nation has acted. Note that Jeremiah never puts himself above his people. He includes himself: “Let us…”
Then they should return to the Lord, first through prayer. Prayer can be insincere. The people in Isaiah’s time lifted up their hands to God, but their hands were bloody with murder. That is why Jeremiah tells the people to lift up their hands and their hearts to God in heaven. It is also possible to translate these words as, “Let us not lift up our hands, but our hearts.” Compare the instruction in Joel 2:12–13, in which the people are told to tear their hearts, not their clothes.
The basic sin that should be confessed, is the sin of rebellion against God (see notes under chapter 1:14). From this sin, the sin of breaking covenant with God, came all the other sins of Israel. For centuries God had sent his prophets to Israel to warn her, but she remained rebellious.
40 Let us test and examine our ways, and return to the LORD!