Rankin Wilbourne, in the final pages of his book Union with Christ: The Way to Know and Enjoy God:
We have communion with all three persons of the Trinity, each in turn; and each in turn cares for us and ministers to us. This is how union with the cosmic Christ becomes an everyday reality—as the Father, Son, and Holy Spirit impress these truths on our hearts and minds even as we labor to be brought near.
We have communion with the love of God the Father. Perhaps you don’t have trouble believing that Jesus loves you, but God the Father remains a shadowy figure, distant and dark. Adding to this distance, sometimes we speak as if Jesus had to die to convince or coerce his Father into loving us, as if the Father were unwilling. But this is a tragic misunderstanding of God’s heart. It is only because God the Father loved us first, while we were yet his enemies, that he was willing to deliver up his only Son for us (Rom. 8: 32). Such is the love of God the Father, with whom we now have communion. What heights of love!
We have communion with the grace of our Lord Jesus Christ, who is full of “grace upon grace” (John 1: 16). Jesus, the only child of God by nature, is yet not ashamed to welcome us into his family by adoption through his blood. Our communion with God the Father is made possible by the grace of our Lord Jesus, who is our mediator (1 Tim. 2: 5) and who never grows tired of us or weary of dispensing his grace. What depths of peace!
And we have communion with the Holy Spirit, our comforter and advocate. In the courtroom of our conscience, when the voice of our own heart rises up to condemn us (1 John 3: 20), the Spirit of God bears witness with ours that we are God’s children (Rom. 8: 16) and gives us, beyond what words alone could, certainty of our salvation by pointing us back to our Savior (John 16: 14). The Spirit subjectively assures us of what is objectively true. What blessed assurance!