This skateboarder, like many others, did not understand what Jesus did and why He had to die. Unfortunately many have only a vague knowledge of the Gospel. Therefore, it is necessary to use biblical principles to explain it to them.
You can start explaining the Gospel by using God’s Ten Commandments to show how we have all broken God’s law and deserve to be punished. Then, explain how Jesus was punished for us on the cross in place of sinners, and defeated death by rising from the dead. If one repents and trusts in Jesus as Lord and God, they will be saved! The moment one responds to the Gospel, their sins are forgiven and they are seen as righteous because Jesus’s perfect life has been credited to them! “For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God.” (2 Corinthians 5:21, ESV)