What has God already done for a person who is trapped in sin?
God has already done everything needed to set a person trapped in sin free and reconcile them to Himself. The whole triune God, with all His power, was in Christ reconciling the world unto Himself, not imputing their trespasses unto them.
Les explains that God has given us the ministry of reconciliation. As He gives opportunity, we are to be ready to tell the person wrapped in Satan's web that God has done everything that needed to be done to set them free and reconcile them to Himself. Les points to verse 19: the whole triune God, with all His power, was in Christ, reconciling the world unto Himself, not imputing their trespasses unto them, and has committed unto us the word of reconciliation. God has left us here as ambassadors—representatives of a government not in their own homeland but in a strange land. Les warns against simply knocking on doors or grabbing people by the shirt collar, because the Lord does not work that way; instead, we jump on the opportunities He gives.