The church starts with Jesus Christ. He said that he would build his church (Matthew 16:18). Paul said that he laid the foundation of Jesus Christ and that others were building on that foundation (1 Corinthians 3:9-11). He also says that his readers (and us?) should continue building (Ephesians 4:16; 1 Corinthians 14:1-5).
So, Jesus is still building his church, primarily through us. As God works through us by his Holy Spirit, Jesus builds his church.
But, how can we ensure that Jesus is doing the building and not us? We have good ideas and good plans and good motives and good hopes, but is Jesus building the church or are we building the church? Is there a difference? Should we be concerned?