Acts 1:8 (ESV)
8 But you will receive power when the Holy Spirit has come upon you, and you will be my witnesses in Jerusalem and in all Judea and Samaria, and to the end of the earth."
The goal of all believers should be to advance the kingdom. While each person is saved individually, their Christian walk must be lived out in community. By pastors and believers working together in unity and by believers growing in their faith and maturing to the point of living out what Jesus commanded, the kingdom will advance. This takes complete cooperation and unity. Christians are not on earth to build themselves up, we are here to worship and glorify God. By being witnesses, we will be able to see the kingdom advance.