According to the Great Commission found in Matthew 28:19-20, Christians are commanded to preach and teach the gospel to all nations. This command simply means that one of the primary duties of all believers is to reach out to those who have not obeyed the gospel. In Luke 19:10, Jesus said, "For the Son of Man came to seek and to save the lost." This means Jesus' mission was to bring all of humanity unto Him and into His church. Since believers are Christians, which means like Christ, then it is our duty to emulate Christ by being seekers of the lost.