Union with Christ by means of the Holy Spirit is not a peripheral matter in biblical theology, although it is widely neglected. It is a key thought in the Lord’s teaching, as this lecture will show, and it is so important to Pauline theology that one commentator rightly calls it ‘the heart of Paul’s religion’, writes Reverend Vaka Ngaro of Cook Islands Christian Church.

The subject of spiritual union is the most important, the most profound, and yet the most blessed of any that is set forth in the sacred Scriptures; and yet, sad to say, there is hardly any which is now more generally neglected. The very expression ‘spiritual union’ is unknown in most professing Christian circles, and even where it is employed it is given such a protracted meaning as to take in only a fragment of this precious truth.

As with most New Testament teachings, the seeds of this doctrine are in the recorded words of Jesus, in this case conveyed under various metaphors and pictures. One key metaphor is that of the vine and its branches: “Abide in me, and I in you. As the branch cannot bear fruit by itself, unless it abides in the vine, neither can you, unless you abide in me. I am the vine, you are the branches. He who abides in me, and I in him, he it is that bears much fruit, for apart from me you can do nothing.” (John 15:4 5). 

In the high priestly prayer of the Lord recorded in John 17 this union is discussed explicitly: “I do not pray for these only, but also for those who believe in me through their word, that they may all be one; even as thou, Father, art in me, and I in thee, that they also may be in us, so that the world may believe that thou hast sent me ... I in them and thou in me, that they may become perfectly one, so that the world may know that thou hast sent me and hast loved them even as thou hast loved me.” (vv.  20 21, 23).

In the writings of Paul this doctrine receives its greatest development and emphasis. We think of the important Pauline formulas, “in him,” “in Christ, “in Christ Jesus,” which occur many times in his writings. 

Firstly, looking back, the fountain of salvation lies in the eternal election of the individual by God the Father in Christ. This is the meaning of the full text from Ephesians 1, parts of which were cited above: “Blessed be the God and Father of our Lord Jesus Christ, who has blessed us in Christ with every spiritual blessing in the heavenly places, even as he chose us in him before the foundation of the world.” (Eph. 1:3 4). We may not understand the full meaning of this eternal election in Christ, but at least we can understand that as far back as we can go, we find that God’s purposes for us involved our salvation.  Salvation is not an afterthought. It was there from the beginning.

The first work performed by the Holy Spirit in our behalf was to elect us members of Christ’s body. In his eternal decrees God determined that he should not be solitary forever, that out of the multitude of sons of Adam a vast host would become sons of God, partakers of the divine nature and conformed to the image of the Lord Jesus Christ. This company, the fulness of him who fills all in all, would become sons by the new birth, but members of the body by the baptism of the Holy Spirit.

Secondly, in the present we are united with Christ in our regeneration or new birth. Jesus spoke of this to Nicodemus saying, “Unless one is born of water and the Spirit, he cannot enter the kingdom of God” (John 3:5). Paul amplified it noting, “If anyone is in Christ, he is a new creation.” (2 Cor.  5:17).