It is important to note that Owen maintains an essential distinction between union and communion.
Believers are united to Christ in God by the Spirit. This union is a unilateral action by God, in which those who were dead are made alive, those who lived in darkness begin to see the light, and those who were enslaved to sin are set free to be loved and to love. When one speaks of “union,” it must be clear that the human person is merely receptive, being the object of God’s gracious action. This is the state and condition of all true saints.
Communion with God, however, is distinct from union. Those who are united to Christ are called to respond to God’s loving embrace. While union with Christ is something that does not ebb and flow, one’s experience of communion with Christ can fluctuate.
This is an important theological and experiential distinction, for it protects the biblical truth that we are saved by radical and free divine grace.
Furthermore, this distinction also protects the biblical truth that the children of God have a relationship with their Lord, and as a relationship, there are things that can either help or hinder it. When a believer grows comfortable with sin (whether sins of commission or sins of omission) this invariably affects the level of intimacy this person feels with God. It is not that the Father’s love grows and diminishes for his children in accordance with their actions, for his love is unflinching. It is not that God runs from us, but we run from him. Sin tends to isolate the believer, making him feel distant from God. Then come the accusations—both from Satan and self—which can make the believer worry he is under God’s wrath. In truth, however, saints stand not under wrath, but in the safe shadow of the cross.
While a saint’s consistency in prayer, corporate worship, and biblical meditation are not things that make God love him more or less, such activities tend to foster the beautiful experience of communion with God. Temptations and neglect threaten the communion, but not the union [Works, 2:126]. And it is this union which encourages the believer to turn from sin to the God who is quick to forgive, abounding in compassion, and faithful in his unending love.
Let there be no misunderstanding—for Owen, Christian obedience was of utmost importance, but it was always understood to flow out of this union, and never seen as the ground for it. In harmony with Bunyan and other Dissenters like him, Owen “insisted upon a very personal and emotional experience of union with Christ and the Holy Spirit,” and out of this union naturally flowed active communion.
Kelly M. Kapic, “Worshiping the Triune God: Insights from John Owen,” introduction to John Owen, Communion with the Triune God, ed. Kelly M. Kapic and Justin Taylor; foreword by Kevin J. Vanhoozer (Wheaton, IL: Crossway, 2007), pp. 21-22.