The Baptism in the Spirit is a phrase used in Scripture to describe the experience wherein the Holy Spirit enters the Temple of God, i.e., the body of a Son of God. The Holy Spirit, who brought the sinner to repentance and begat him again into the family of God, desires a still closer union, whereby He that was "with us" now enters "into us." As an evidence that He has entered the believer's body, He begins to use the most unruly part of it, i.e., the tongue, to speak in a language of which the believer is ignorant; thus making it manifest that there are now two occupants of the one body.
The Baptism of the Spirit is spoken of by John Baptist and Christ as a vital element in the work of Salvation He came to procure. (John 1:29-33, 7:37-39, 16:7-15, 14:17, 2:21, Lk. 24:49, Acts 1:4-8, 2:3-21, 10:44-48, 11:15-17, 19:1-6, Mk. 16:17, I Cor. 3:16, 6:19, II Cor. 6:16.)
The actual Baptism in the Spirit is, however, only the initial experience of a fellowship which is to be eternal; and the initial evidence is meant to be followed by further manifestations of the Spirit's presence. The New Testament Church is a society of the Sons of God, in whose bodies dwells the same Holy Spirit of God, manifesting His Almighty presence by the various miraculous Gifts of the Spirit. (I Cor. 12:1-14:40.)
The Church, the present earthly Body of Christ, who is its head, is therefore to be indwelt by the Holy Spirit of God, even as was Christ's own earthly body, so that the will of God may continue to be done by the Spirit of God in the Sons of God. (John 14:16-26, 15:26, II Cor. 3:17-18, Acts 4:31, 5:3, 32, 7:51, 52, 8:29, 39, 13:2. etc.)
N.B.1. In the Old Covenant it was the Holy Spirit who laid hold of the chosen Servants of God, even against their desire, that they might perform the task allotted to them. The instances of Moses, Amos, Jonah, Jeremiah and Ezekiel spring to the mind.