Jurgen Moltmann offers us some thought-provoking words about the Holy Spirit, the Trinity, and the way that we ourselves are drawn into fellowship with God:

If it is true that in the fellowship of the Holy Spirit we experience the nearness of Christ's grace and the presence of God's love, not the influence of a divine power, then deeper dimensions still can be found in this divine fellowship. For the Holy Spirit doesn't merely enter into his own fellowship with us, and doesn't merely take us into fellowship with him. The Spirit himself - herself - exists in fellowship with the Father and the Son 'from eternity to eternity,' and 'together with the Father and the Son is worshipped and glorified,' as the Nicene Creed says. So in the Spirit's fellowship with us is hidden his eternal fellowship with Christ and the Father of Jesus Christ.

The 'fellowship of the Holy Spirit with us' corresponds to his eternal divine fellowship. It does not merely correspond to it; it is that very fellowship itself. So in the fellowship of the Spirit we are linked with the triune God, not externally but inwardly. So in the fellowship of the Holy Spirit with us all, we experience the nearness of the divine life, and also experience our own mortal life as life that is eternal. We are 'in God' and God is 'in us.'

In the fellowship of the Holy Spirit the divine Triunity is so wide open that the whole creation can find room in it.

--The Source of Life by Jurgen Moltmann, pp. 90-91