The apostle Peter urged: “Repent, therefore, and turn around so as to get your sins blotted out, that seasons of refreshing [rather than wrath] may come from the person of Jehovah.” (Acts 3:19)
... 7. What is the symbolic mark?
7 The symbolic mark is the evidence, as if displayed on your uncovered forehead, (1) that you are a dedicated, baptized disciple of Jesus Christ and (2) that you have put on the Christlike new personality. (Ephesians 4:20-24)