To say that our union with Christ is Trinitarian means that by virtue of being incorporated into the life of Jesus Christ, we participate in the life, love, and fellowship of the Trinity. Because the Son is is one with the Father, our being joined to the Son means we are joined to the Father. And because the Spirit exists as the bond of communion between the Father and the Son, he brings us into that communion by uniting us to Christ. This staggering biblical revelation forms the personal foundation for all the benefits that constitute our salvation.
Marcus Peter Johnson, One with Christ: An Evangelical Theology of Salvation, (Weaton, Ill: Crossway, 2013), p. 42