The Law of Moses (cf. Leviticus 20:10; Deuteronomy 22:22, 23-24) required death for adulterers and death by stoning in a specific circumstance. With this in mind the Scribes and Pharisees brought a woman “caught in adultery” before Jesus to see how he would judge her (John 8:3-4). Theirs was not an honest question. They questioned him as a test, “so that they could have some charge to bring against him” (John 8:6). They want to catch Him compromising the Law of Moses. What does Jesus do? “Jesus bent down and began to write on the ground with his finger” (John 8:6). What a curious thing to do!
Many have attempted an explanation. My favorite, however, is one that sees this gesture as a reference to Jeremiah 17:13: “Those who turn away from thee shall be written in the earth, for they have forsaken the Lord, the fountain of living water” (Revised Standard Version). The Scribes and Pharisees are not interested in fulfilling the Law. They want to trap Jesus. They have turned away from Him and merit to be written in the soil. This, I find, helps us understand the concluding admonition of Jesus: “Let the one among you who is without sin be the first to throw a stone at her” (John 8:7). Jesus is not condoning sin. Neither is He permissively looking the other way. He is confronting those who would reject Him and His message. Once the accusers shamefacedly depart, He can then address the sin of the woman. She is now without accusers (John 8:11). But what of the sin? Jesus concludes, “Neither do I condemn you. Go, and from now on do not sin any more” (John 8:11).
Jesus challenges those who would reject Him and gently allows the Divine Mercy to call a sinner to repentance.