The Spirit is not only the life-giving Spirit but also the Spirit of life (Rom. 8:2). The Spirit of life is the reality of life, for this Spirit contains the element of the divine life. Actually, the Spirit Himself is life. Therefore, with the Spirit of life we have the riches of the divine life.
The way to have life is the Spirit. Life belongs to the Spirit, and the Spirit is of life. The two are actually one. We cannot separate life from the Spirit, nor the Spirit from life. If we have the Spirit, we have life. If we do not have the Spirit, we do not have life. The way to experience the divine, eternal, uncreated life is the Spirit of life.
In Romans 8:9 Paul speaks of the Spirit of God dwelling in us, and in verse 14, of the sons of God being led by the Spirit of God. We should not understand the title the Spirit of God to mean that the Spirit is something from God. In the New Testament phrases such as the love of God and the life of God mean that love and life are God Himself. In the same principle, the term the Spirit of God means that the Spirit is God. Hence, for us to be indwelt and led by the Spirit of God means that we are indwelt and led by God Himself.
The Spirit of Jesus (Acts 16:7) is a particular expression concerning the Spirit of God and refers to the Spirit of the incarnated Savior who, as Jesus in His humanity, passed through human living and death on the cross. This indicates that the Spirit of Jesus contains not only the divine element but also the human element and the elements of Jesus' human living and His suffering of death.
In Romans 8:9 Paul speaks of the Spirit of Christ. The Spirit of Christ is related to the Lord's death and resurrection. The Spirit of Christ is the Spirit of the One who passed through death and entered into resurrection. The Spirit of Christ is the totality, the aggregate, of the all-inclusive Christ with His all-inclusive death and resurrection.
The Spirit of Jesus Christ (Phil. 1:19) is "the Spirit" mentioned in John 7:39. This is not merely the Spirit of God before the Lord's incarnation but the Spirit of God, the Holy Spirit with divinity, after the Lord's resurrection, compounded with the Lord's humanity, human living under the cross, crucifixion, and resurrection.
Because the Spirit of Jesus has particular reference to the Lord's suffering, and the Spirit of Christ to His resurrection, the Spirit of Jesus Christ is related to both His suffering and His resurrection. The Spirit of Jesus Christ is the Spirit of the Jesus who lived a life of suffering on earth and of the Christ who is now in resurrection. The reality of such a Jesus and such a Christ is the Spirit of Jesus Christ.