When Jesus started to preach, then he started to invite people to become kings that will rule with him over mankind on earth. So the Christian Greek scriptures are focused on that purpose. For the new government to function well, the kings that will rule together with Jesus have to become very good as persons. That is the main thing taught in the New Testament.
2 Timothy 2:12 if we go on enduring, we will also rule together as kings; if we deny, he will also deny us;
1 Corinthians 4:8 Are you already satisfied? Are you already rich? Have you begun ruling as kings without us? I really wish that you had begun ruling as kings, so that we also might rule with you as kings.