What does Proverbs 20:9 mean?

Some statements are phrased as questions—the obvious answer is meant to make a point. In Mark 8:4, Jesus' disciples ask where they could get bread to feed a large crowd. The purpose of their "question" was really an expression of their despair. In that case, Jesus miraculously intervened (Mark 8:5–8). This proverb is another example. By asking what person can claim to be sinless, Solomon echoes a common teaching of the Bible (Romans 3:10; 1 John 1:8–10). It's possible for a person to be "blameless" in the sense that they give no reason for others to criticize their morals (Job 1:1; Psalm 15:1–2; Luke 1:6; Philippians 2:15; Titus 1:6–7). Yet no person is morally perfect in the eyes of God (Romans 3:23).

A person may claim to have a spotlessly clean heart, free from all sin, but the Bible contradicts such suggestions. Jeremiah 17:9 declares, "The heart is deceitful above all things, and desperately sick." Romans 3:9–18 includes a list of indictments against humanity.

Purity in God's sight cannot originate with any man; it comes only to those who believe on Jesus Christ as their Savior (John 3:36). Only Christ lived a sinless life (Hebrews 4:15). His sacrificial death paid penalty sufficient for the sins of the whole world (1 John 2:2). Yet only those who accept Him as Savior receive forgiveness and cleansing (John 3:16–18). Revelation 1:5 ascribes praise to Christ as the one "who loves us and has freed us from our sins by his blood." Paul writes in 2 Corinthians 5:21: "For our sake [God] made [Jesus] to be sin who knew no sin, so that in him we might become the righteousness of God."