The main idea in Jonathan Edwards' sermon titled "Sinners in the Hands of an Angry God" is that of Romans 3:23 in the Bible.
Romans 3:23 states that "All have fallen short of the glory of God," and because of this, God's wrath towards sinful people is an act of justice. In his sermon, Jonathan Edwards encourages his audience to flee from sin and turn to good works out of love for Jesus Christ.