When our Lord Jesus was giving His farewell address to His disciples the night before His crucifixion, they desperately needed comfort. Having been with Christ for over three years, they faced the grim prospect of being separated from the Lord. How could they go on to an impossible mission without Him? This need for power and fellowship with Christ was met through the promise of the Holy Spirit. When He would come on Pentecost to baptize God’s people, believers would be personally united with Christ. Then, whether in Jerusalem or the ends of the earth, Christ would be present in their hearts! (John 14:16-18).
As Christians, we tend to overlook the significance of this union with Christ. Missions leader Norman Grubb observed, “Very often from our pulpits no nearer presentation of Christ is given to the believer than that He is a Friend close at hand, and so forth. The veil of a false separation is left over the eyes.” And what consequences arise from this? Grubb continued: “Here … lies the great error. It leaves man to do the very thing he was never created nor redeemed to do, to carry on as best he can by self-effort, helped, he hopes, by the presence and blessing of God. For most of us this deeper revelation of union has to come as a second experience. We can seldom see our outward sins and inner selves in one single exposure … The twofoldness is not on His [God’s] side. But for most of us there has to be a twofold appropriation of the great deliverances that stream from one Calvary, the deliverance from sin and wrath (Rom 1-5), [and] the deliverance from sin and independent self (Rom 6-8).” 
The believer’s spiritual union with the risen Christ is pictured in various ways in the New Testament. We are joined to Him as members of a physical body to the head (1 Cor 6:15,17,19;12:12; Eph 1:22), as a wife is to her husband (Rom 7:4; Eph 5:31-32), as descendants are connected to Adam (Rom 5:12,18-21; 1 Cor 15:22), and as a building is based on its foundation (1 Cor 3:11; Eph 2:20-22). However, the most vivid metaphor of the spiritual union of Christ and His people is the imagery of John 15: “I [Jesus] am the true vine, and My Father is the vinedresser … Abide in Me, and I in you. As the branch cannot bear fruit of 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, bears much fruit; for without Me you can do nothing” (vv.1-5).
What are the implications of this spiritual union of the believer with Christ?  Scripture speaks of four key events in our Savior’s redemptive work that become banners of blessing in the life of the child of God. The disciple of Christ is united to Him in His death, burial, resurrection, and ascension. Let’s look more closely at these four aspects of our Savior’s work for and in us.
1. Believers are united to Christ in His death. Galatians 2:20 proclaims: “I have been crucified with Christ; it is no longer I who live, but Christ lives in me; and the life which I now live in the flesh I live by faith in the Son of God, who loved me and gave Himself for me.” And Romans 6:6 declares, “knowing this, that our old man was crucified with Him, that the body of sin might be done away with, that we should no longer be slaves of sin.”
Because we are united to Christ in His death, we are free from condemnation! The true believer need not be burdened by any guilt; Christ proclaimed on Calvary “It is finished!” (John 19:30). “Therefore, [there is] now no condemnation — no adjudging guilty of wrong — to those who are in Christ Jesus…” [Amplified; Cf. Col 2:13-14].
2. Believers are united with Christ in His burial. “Or do you not know that as many of us as were baptized into Christ Jesus were baptized into His death? Therefore we were buried with Him through baptism into death…” (Rom 6:3-4). What is the significance of burial? It is a testimony of separation from the previous realm of life.
Since believers are buried with Christ, they are free from sin’s authority. In Adam’s line, unsaved man was under sin’s dominion –sinning because of being a sinner. “For when you were slaves of sin [before salvation], you were free in regard to righteousness. … But now having been set free from sin, and having become slaves of God, you have your fruit to holiness, and the end, everlasting life. For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord” (Rom 6:20-23 Cf. v.7). Sin is not out of calling distance, but believers are FREE from its authority. Living in this freedom is a matter of faith!
Also, believers are separated from the realm of the law. “For sin shall not have dominion over you, for you are not under law but under grace” (Rom 6:14). Under the Old Covenant, the Mosaic Law was like a schoolmaster: “before faith came, we were kept under guard by the law, kept for the faith which would afterward be revealed. Therefore the law was our tutor to bring us to Christ, that we might be justified by faith. But after faith has come, we are no longer under a tutor” (Gal 3:22-25). Now we are under the law of love — the law of Christ (Gal 6:2; James 2:8). And as we walk in the Spirit, we fulfil the righteous requirements of God’s unchanging moral law (Rom 8:4).
3. Believers are united with Christ in His resurrection. “But God, who is rich in mercy, because of His great love with which He loved us, even when we were dead in trespasses, made us alive together with Christ (by grace you have been saved) and raised us up together” (Eph 2:4-6a; Col 3:1).
Because of this union, we are partakers of Christ’s resurrection life! “But if the Spirit of Him who raised Jesus from the dead dwells in you [as in all believers – v. 9], He who raised Christ from the dead will also give life to your mortal bodies [power to live abundantly] through His Spirit who dwells in you” (Rom 8:11). Therefore we have the resources to walk in newness of life! (Rom 6:4). “Likewise you also, reckon yourselves to be dead indeed to sin, but alive to God in Christ Jesus our Lord” (Rom 6:11; Cf. Eph 1:15-21). As we realize the power we have through our spiritual union with Christ. God’s will becomes our ability, desire, and delight (Phil 2:13).
4. Believers are united with Christ in His ascension. “If then you were raised with Christ, seek those things which are above, where Christ is, sitting at the right hand of God. Set your mind on things above, not on things on the earth. For you died, and your life is hidden with Christ in God. When Christ who is our life appears, then you also will appear with Him in glory” (Col 3:1-4). And Ephesians 2:6 confirms that God, “raised us up together, and made us sit together in the heavenly places in Christ Jesus.”
Since we are united with Christ in His ascension, we partake of His authority, and His authority is supreme (Matt 28:18). We are to fully submit to His authority as His people, yet we are beneficiaries of His authority also. We are joint-heirs with Christ! (Rom 8:17).
In Christ we have authority in prayer and spiritual warfare. Christ promised us, “If you abide in Me, and My words abide in you, you will ask what you desire, and it shall be done for you” (John 15:7; Cf. 16:23-24). And since Satan is a defeated foe, we are partakers of Christ’s victory: “Therefore submit to God. Resist the devil and he will flee from you” (James 4:7 Cf. Col 2:14-15).
Charles Trumbull testified of the blessings he experienced when he understood and appropriated by faith his union with Christ: “To begin with, I realized for the first time that the many references in the New Testament to Christ in you, and you in Christ, Christ our life, and abiding in Christ, are literal, actual, blessed fact, and not figures of speech. How the 15th chapter of John thrilled with new life as I read it now! (Cf. Eph 3:14-21; Gal 2:20; Phil 1:21). What I mean is this: I had always known Christ was my Saviour; but I had looked upon Him as an external Saviour, one who did a saving work for me from outside, as it were; one who was ready to come close alongside and stay by me, helping me in all that I needed, giving me power and strength and salvation. But now I knew something more than that. At last I realized that Jesus Christ was actually and literally within me; and even more than that: that He constituted Himself my very life, taking me into union with Himself — my body, mind, and spirit — while I still had my own identity and free will and full moral responsibility… It meant that I need never again ask Him to help me as though He were one and I another; but rather simply to do His work, His will, in me, and with me, and through me.” 
In light of this spiritual union, “the Christian is a mind through which Christ thinks; a heart through which Christ loves; a voice through which Christ speaks; a hand through which Christ helps.” Fellow believer, do you reckon this true for yourself?