Doctrine of Union with Christ
I. Definition
A. The phrase “in Christ” are the most frequent terms used to identify this teaching of union with Christ (U/C).

2 Cor. 5:17 Therefore, if anyone is in Christ, he is a new creation; old things have passed away, behold, new things have come!

Greek e˙n Cristwˆ◊, en Christoœ

Two topics are addressed in this verse:
1) The man in Christ, who is a new creation.
2) Things—Old things (neuter plural) have passed away, new things (neuter plural) that have come.

The first topic,man explained:
The instant we are saved, we are immediately united with Christ, we are a new creation. Union with Christ is not a gradual process. Our position and our relationship is changed from being separated from Christ to a entirely opposite situation—now we are united with Christ. God the Father is the believer’s heavenly Father and he shares a sonship with the Son of God, Jesus Christ.

The second topic explained.
The old and new things refer to things within the larger picture of the “old age” or “evil age” (Gal. 1:4) that is still present and the “new age” that has broken in—as Phase I Kingdom of God (e.g. Matt. 12:28;Lu. 11:20).

B. Summation: To be in Christ is to live in the realm of the new age, Kingdom of God, Phase I and as a new creation in that age. The believer is so connected to Christ that he experiences the power of the Spirit and the freedom from sin.

C. All believers are in Christ.

Gal. 3:28 There is neither Jew nor Greek, there is neither slave nor free, there is neither male nor female–for all of you are one in Christ Jesus.

II. Being “in Christ” is part of a larger concept of the believer who shares or partakes in the divine nature of all three members of the Trinity and they in him.
A. We share in the divine nature of God.

2Pet. 1:3 ¶ His divine power has given us everything we need for life and godliness through our knowledge of him who called us by his own glory and goodness.
2Pet. 1:4 Through these (glory and goodness) he has given us his very great and precious promises, so that through them you may participate in the divine nature and escape the corruption in the world caused by evil desires.

B. The believer may be filled up with all the fullness of God.

Eph. 3:19 and to know this love that surpasses knowledge—that you may be filled to the measure of all the fullness of God.

C. Believers are sharers in Christ and all that he has to offer.

Heb. 3:14 We have come to share in Christ if we hold firmly till the end the confidence we had at first.

D. The believer who is in Christ is also in the Spirit. He shares the Spirit.

Rom. 8:9 But you are not in the flesh (an unbeliever) but in the Spirit (believer), if indeed the Spirit of God dwells in you. And if anyone does not have the Spirit of Christ, he does not belong to him.

E. The believer is in Christ who is in the Father.

John 14:20 “In that day you will know that I am in My Father, and you in Me, and I in you.

“that day”-is the day the believer receives the Spirit.
(Jn. 14:16-17)

F. The believer in Christ shares all three members of the God through the Spirit, who lives/abides in every believer.

III. The church, as the body of Christ, also shares in a union with Christ.
A. The Church

Eph. 5:31 “For this reason a man will leave his father and mother and be united to his wife, and the two will become one flesh.”
Eph. 5:32 This is a profound mystery—but I am talking about Christ and the church.

Gal. 1:22 I was still unknown by sight to the churches of Judea which were in Christ;

Rom. 12:5 so in Christ we who are many form one body, and each member belongs to all the others.

B. Includes both Jews and Gentiles.

Eph. 3:6 This mystery is that through the gospel the Gentiles are heirs together with Israel, members together of one body, and sharers together in the promise in Christ Jesus.

IV. The concept of union with Christ was a mystery,
A. It is now revealed to the saints.

Col. 1:26 that is, the mystery that has been kept hidden from ages and generations, but has now been revealed to his saints,

B. It is a mystery of glorious riches.

Col. 1:27 to whom God wanted to make known what is the riches of the glory of this mystery among the Gentiles, which is Christ in you, the hope of glory.

V. Characteristics of Union with Christ.
A. It is judicial in that it is such a nature that believer as so identified as one that when the Father sees the righteous Son, he also sees a righteous believer.
The two are viewed as one.

Rom. 8:1 Therefore, there is now no condemnation for those who are in Christ Jesus,

B. It is spiritual in that the Holy Spirit baptized the believer in Christ, identifying him with Christ at the point of salvation.

1Cor. 12:13 For we were all baptized by one Spirit into one body—whether Jews or Greeks, slave or free—and we were all given the one Spirit to drink.

Rom. 8:10 And if Christ is in you (through the Spirit), though the body is dead because of sin yet the Spirit is life because of righteousness.

Rom. 8:11 Moreover, if the Spirit of the One (God) who raised Jesus from the dead dwells in you, the One (God) who raised Christ (Jesus*) from the dead will also make alive your mortal bodies through his Spirit who lives in you.

We see here the very close connection between Christ and the Spirit. Since the Spirit lives in you, he will give you life to live—that is power to live as a Christian (Eph. 3:16)

VI. Union with Christ is essential for spiritual production.

John 15:4 Remain in me, and I will remain in you. No branch can bear fruit by itself; it must remain in the vine. Neither can you bear fruit unless you remain in me.
John 15:5 ¶ “I am the vine; you are the branches. If a man remains in me and I in him, he will bear much fruit; apart from me you can do nothing.
John 15:6 If anyone does not remain in me, he is like a branch that is thrown away and withers; such branches are picked up, thrown into the fire and burned.

VII. It empowers the believer for life.

Gal. 2:20 I have been crucified with Christ and I live no longer but Christ lives in me. And which life I live now in the flesh (body), I live by faith which is of the Son of God who loved me and gave himself for me.

Phil. 4:13 I have strength to do all things through Him who empowers me.

2Cor. 12:9 But he said to me, “My grace is sufficient for you, for my power is made perfect in weakness.” Therefore I will boast all the more gladly about my weaknesses, so that Christ’s power may rest on me.

Rom. 6:11 ¶ In the same way, count yourselves dead to sin but alive to God in Christ Jesus.

VIII. Sharing different aspects of Christ’s human experience.
A. Baptism into Christ is identifying with Him.

Mark 10:39 ¶ “We can,” they answered. ¶ Jesus said to them, “You will drink the cup I drink and be baptized with the baptism I am baptized with,

B. Share in His suffering.

John 15:20 “Remember the word that I said to you, ‘A slave is not greater than his master.’ If they persecuted Me, they will also persecute you; if they kept My word, they will keep yours also.

1Pet. 4:13 But rejoice that you participate in the sufferings of Christ, so that you may be overjoyed when his glory is revealed.

C. Share in his death and resurrection.

Phil. 3:10 I want to know Christ and the power of his resurrection and the fellowship of sharing in his sufferings, becoming like him in his death,

Phil. 3:11 and so, somehow, to attain to the resurrection from the dead.

Rom. 6:4 We were therefore buried with him through baptism into death in order that, just as Christ was raised from the dead through the glory of the Father, we too may live a new life.

Rom. 6:5 ¶ If we have been united with him like this in his death, we will certainly also be united with him in his resurrection.

Rom. 6:6 For we know that our old self was crucified with him so that the body of sin might be done away with, that we should no longer be slaves to sin—

Rom. 6:7 because anyone who has died has been freed from sin.

Rom. 6:8 ¶ Now if we died with Christ, we believe that we will also live with him.

D. Share in His reign

2Tim. 2:12a if we endure,we will also reign with him.

E. Share in the Father’s love.

Rom. 8:39 neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord.

IX. The believer’s blessings in Christ are many.

Eph. 1:3 Blessed be the God and Father of our Lord Jesus Christ, who has blessed us with every spiritual blessing in the heavenly realms in Christ,

1. Every spiritual blessing. Eph. 1:3
2. Resurrection. 1 Thess. 4:16
3. Made alive. 1 Cor. 15:22
4. Chosen in Christ Eph. 1:4
5. Redemption Rom. 3:24
6. Forgiveness of sins Eph. 1:7;4:32
7. Sanctification 1 Cor. 1:2
8. Reconciliation 2 Cor. 5:19
9. Justification Gal. 2:17
10. Brought to God Eph. 2:12
11. Salvation 2 Tim. 2:10
12. Encouragement Phil. 2:1
13. Peace of God Phil. 4:7
14. Strength Phil. 4:17
15. God’s workmanship Eph. 2:10
16. Grace 1 Cor. 1:4
17. Enriched in speech and knowledge 1 Cor. 1:5

Many of our most basic doctrines in the Doctrine of Salvation or Soteriology are related to the doctrine of Union with Christ.