You did it! You just shared the Law and the gospel with an unbeliever. Well done! But, your evangelistic task is not complete. Now that you have given the cure to their disease, you must rightly tell them how to appropriate the cure. Failing to give the right salvation instructions is worse than a doctor who diagnoses an illness but writes a prescription with the wrong directions. The results are deadly.
What should we tell people they must do to be saved? The same thing the Bible tells them: repent and believe the gospel. Over thirty times the New Testament commands repentance and faith.
Jesus came into Galilee, preaching the gospel of God, and saying, “The time is fulfilled, and the kingdom of God is at hand; repent and believe in the gospel.” (Mark 1:15)
[Paul was] solemnly testifying to both Jews and Greeks of repentance toward God and faith in our Lord Jesus Christ. (Acts 20:21)
Repentance is essential to salvation. As Charles Spurgeon said, “Sin and hell are married unless repentance proclaims the divorce.” God commands all men everywhere to repent (Acts 17:30), and is “not willing that any should perish but that all should come to repentance” (2 Peter 3:9).