We were born into a human family where we immediately belonged. As we grew we learned by experience that we had parents and most likely siblings that were a part of our lives and where we felt a part of theirs. We belonged! What a great feeling that is! In this verse Paul makes it very clear that Christ has made us a part of God's dwelling place! God has prepared a home for us and that home is where He lives! And its your home too!
Do you feel a sense of "belonging" to Christ? Do you feel that amongst His people? Do you make an effort to help other believers feel that sense as well? That's what Paul is doing - he is making us feel we belong to Christ. We're a part of Him and His family and He and His family are a part of us! Enjoy your security in Him!