Communion with God Demands Union with Christ
John Newton writes about the centrality of Christ in our fellowship with God:
Communion presupposes union. By nature we are strangers, yea, enemies to God; but we are reconciled, brought nigh, and become his children, by faith in Christ Jesus. We can have no true knowledge of God, desire towards him, access unto him, or gracious communications from him, but in and through the Son of his love.
He is the medium of this inestimable privilege: for he is the way, the only way, of intercourse between heaven and earth; the sinner's way to God, and God's way of mercy to the sinner. If any pretend to know God, and to have communion with him, otherwise than by the knowledge of Jesus Christ, whom he hath sent, and by faith in his name, it is a proof that they neither know God nor themselves.
God, if considered as abstracted from the revelation of himself in the person of Jesus, is a consuming fire; if they should look upon us without respect to his covenant of mercy established in the Mediator, we could expect nothing from him but indignation and wrath. But when his Holy Spirit enables us to receive the record which he has given of his Son, we are delivered and secured from condemnation; we are accepted in the Beloved; we are united to him in whom all the fullness of the Godhead substantially dwells, and all the riches of divine wisdom, power, and love, are treasured up.
The Works of John Newton, vol. 1, 1820, (Carlisle, PA: Banner of Truth Trust, 2007) 306, paragraphing mine.
See Pastor John's biography of John Newton, "The Tough Roots of His Habitual Tenderness."