The union of Christ is mentioned and referenced throughout New Testament scripture. It is a phrase that many have a hard time defining. Regarding the subject, Paul himself said, “This is a profound mystery.” (Eph. 5:32) Basically, the union that the believer has with Christ pertains to the entirety of salvation. According to John Murray, “the various other doctrines are simply subparts.” (i.e regeneration, justification, and sanctification.) Paul states hundreds of different phrases implying the unity that the believer has with Christ. He uses phrases like: “In Christ”, “with Christ”, and “In Him” (along with others) to represent the connection and unity between the believer and Jesus.
The unity that we share with Christ is one of the most crucial aspects regarding the doctrine of salvation. As Murray stated, “it is an inclusive term for the whole of salvation.” Millard J. Erickson explains the three main characteristics of the union in Chapter 34 of his book; Introducing Christian Doctrine. He points out that the union with Christ is judicial, spiritual, and vital. It is judicial because those “in Christ” will no longer have to stand alone before the judgement of God. God himself no longer sees simply an unrighteous sinner, because Jesus lives within the believer, making one holy and righteous in the sight of God. The union with Christ is also spiritual. It is affected and maintained by the Holy Spirit. The Holy Spirit is the believer’s bridge/ connection to Christ. Lastly, the union with Christ is vital. According to Erickson, “His life actually flows into ours, renewing our inner nature.” It revives us. It keeps us where we are supposed to be. The union that Christians share with Christ not only redeems one’s sins before God but also allows one to live with Christ’s strength. Ultimately being “In Christ” or “with Christ” means that you will be able to spend eternity with our creator and reign with him one day in glory.
John Murray, Redemption Accomplished and Applied (Grand Rapids: Eerdmans, 1955)
Erickson, M. J. (2015). Introducing Christian Doctrine (3rd ed.). Grand Rapids, MI: Baker Publishing Group.