Even with the hurting Jesus spoke of sin, because without sin, the message of the gospel is meaningless. If we had no sin, we would not be enemies of God, we would not be under His judgment, we would not need reconciliation with God, nor salvation from His justice.
Most people are not murderers, rapists, bank robbers, and child abusers. Most people’s sins are of the ‘milder’ sort: lying, gluttony, jealously, gossip, laziness, cowardice. We don’t see ourselves as ‘bad’ people because we don’t see our sins as ‘bad sins’. Consequently, most people expect God to freely allow them access to His glory on the basis of their being ‘good’ people, and do not see a need for Christ to save them. Without conviction of sin, people will not believe themselves lost, nor in need of a Saviour, and most people will reject the gospel for themselves and die unsaved.
To the adulterous woman in John 8, Jesus was merciful, not allowing the men to stone her in accordance with the Law of Moses. But He also told her ‘go and sin no more’. He likewise told the lame man made whole that he should go and sin no more. He had no glaring, obvious sin, but the admonition was the same. Despite his limitations and hard life, and the rejection and devaluation of his neighbours, Jesus knew that this man, like all men, was a sinner in need of salvation; he was one of the lost Christ came to save.
What is the offense of the cross? That men are lost, dead in their sins and trespasses, and their own righteousness cannot buy them into heaven. Only by repenting from sin and turning in faith to the crucified and risen Lord will anyone be redeemed, for ‘God resists the proud, but gives grace to the humble.” Unless we humble ourselves before Him, admitting our guilt and receiving His grace, we will remain dead in our sins for eternity. Without knowledge of our sin, it’s mighty unlikely we will.