Question:
Why does it say "Christ liveth in me" ?
Does the Holy Spirit not live in us? If we are to believe the trinitarian doctrine. However that is not what it says here. it says Christ liveth in me
"I through the Law died to the Law, so that I might live to God. I have been crucified with Christ, and it is no longer I who live, but Christ lives in me; and the life that I now live in the flesh I live by faith—faith in the Son of God, who loved me and handed himself over to death for me."
For Paul, the former Pharisee who sought to live in total obedience to the Law and experienced it as a tyranny that held him in thrall, it was an inexpressible relief to know that in Christ’s death and resurrection he was released for life in the new age. That element of the theology of redemption became for him an existential reality: his life under the domination of Law had ended, and life henceforth was fellowship with the risen Christ; or, otherwise expressed, the risen Christ was the continuing source of his life, as he daily lived by faith in the Lord who loved him and died for him.
What it does NOT mean is that the person of God the Father and the person of God the Holy Spirit don't exist. They certainly do exist actually as scripture teaches they do.
God is one essence in three persons fulfilling functional roles.
At the heart of Paul’s view of salvation, however, is not so much new ‘performance’ as new relationship: i.e. restoration to God. Israel looked forward to ‘salvation’ as the lavish pouring out of the Spirit upon them (Is. 32:15; 44:3; Ezek. 36–37; Joel 2), because this was to be the return of God to Israel in transforming grace.
Accordingly:
a. Paul describes both the church and the individual as the eschatological temple which God now indwells by his Spirit (1 Cor. 3:16; 6:19; Eph. 2:22, etc.), and the believer is said to have access to God through the Spirit (Eph. 2:18; cf. Rom. 8:26–27).
b. However, these ideas are Christocentric. Paul’s writings are dominated by a rich ‘in Christ’ mysticism, and his understanding of ‘salvation’ is summarized in such passages as Galatians 2:19–20: ‘I have been crucified with Christ, and it is no longer I who live, but it is Christ who lives in me. And the life I now live in the flesh, I live by faith in the Son of God who loved me and gave himself for me’ (nrsv, cf. 1 Cor. 12:13; 2 Cor. 5:17; Phil. 1:21; 3:10, etc.). Christ, as much as the Father, is the indwelling, self-revealing presence of God, but only through the Spirit of God, now experienced as the Spirit of Christ (Rom. 8:9–11; Phil. 1:19; cf. Gal. 4:6).
If salvation is above all ‘union with Christ’, that union is effected and maintained only through the Spirit. The corollary is stated in Romans 8:9b: ‘anyone who does not have the Spirit of Christ, that person does not belong to him’. Fundamentally, then, the Spirit is ‘the Spirit of adoption/sonship’ (Gal. 4:6; Rom. 8:15).
So we see that God is one but in three persons operating in perfect unity fulfilling different functional roles, exactly what scripture teaches and exactly what the doctrine of the Trinity states.