The bond that unites a man with his fellowman is no less real and close than that which unites him to God: one with them. Grace renews not only our relationship with our fellow human beings, too. We not only learn to say “my Father,” but also “our Father.” It would be unnatural for the children of a family to always meet their father separately, never expressing their desires or their love jointly.
Believers are not only members of one family, but of one body. Just as each member of the body depends on the other, the extent to which the Spirit can dwell in the body depends on the union and cooperation of everyone. Christians cannot reach the full blessing God is ready to bestow through His Spirit until they seek and receive it in fellowship with each other. It was to the 120 praying together in total agreement under the same roof that the Spirit came from the throne of the glorified Lord. In the same way, it is in the union and fellowship of believers that the Spirit can manifest His full power.