In 1 Peter 1:10-12a we see the Spirit as the Spirit of Christ witnessing beforehand the death and glorification of Christ as a revelation to the Old Testament prophets. These verses show that the Spirit of Christ was there already in the Old Testament. When the Old Testament prophets were prophesying concerning Christ, the Spirit of Christ was in them, witnessing to them how and when Christ would die and how and when Christ would be glorified, first in His resurrection and then in His ascension. We may wonder how the Spirit of Christ could have been in the Old Testament. We always consider the element of time, but with Christ, with God, there is no time element. When the prophets in the Old Testament predicted Christ’s death, resurrection, and ascension, the Spirit of Christ within them was witnessing. The Spirit’s witnessing means that the Spirit within them was saying, “What you are speaking now concerning the coming Christ is right.” The Old Testament prophets were not merely motivated by the Holy Spirit to prophesy. While they were prophesying, the Spirit of Christ was witnessing to them.
First Peter 4:14 says that the Spirit of glory rests upon the reproached, persecuted believers. When the believers are being persecuted, being reproached, for Christ’s sake, the Holy Spirit is resting upon them. This Spirit is called the Spirit of glory. Note 2 on 1 Peter 4:14 in the Recovery Version says concerning the Spirit of glory and of God: Literally, the Spirit of glory and that of God. The Spirit of glory is the Spirit of God. The Spirit of glory is the One through whom Christ was glorified in His resurrection (Rom. 1:4). This very Spirit of glory, being the Spirit of God Himself, rests upon the suffering believers in their persecution for the glorification of the resurrected and exalted Christ, who is now in glory.
Second Peter 1:21 says, “For no prophecy was ever borne by the will of man, but men spoke from God, being borne by the Holy Spirit.” According to the context of this verse, prophesying here is predicting. This section of the Word says something concerning the Old Testament prophets’ prophesying, foretelling, or predicting the things concerning Christ. No prophecy was ever carried along by the will of man. Man’s will, desire, and wish, with his thought and solution, are not the source from which any prophecy came; the source is God, by whose Holy Spirit men were carried along, as a ship by the wind, to speak out the will, desire, and wish of God.
The Spirit also confirms that God abides in us. We know that God abides in us because of the Spirit given to us (1 John 3:24; 4:13). The Spirit is within us to confirm that God dwells in us, that God abides in us. Actually, the indwelling Spirit is God, so the Spirit confirms what God does.
The Spirit has the function of confessing that Jesus Christ has come in the flesh (1 John 4:2). Whenever we say in a proper way that Jesus has come in the flesh, that indicates that we have the Holy Spirit within us. At the Apostle John’s time, there was a heresy being spread that Christ was not a man. Such heresy undermines not only the Lord’s incarnation but also His redemption and resurrection. Since Christ was conceived of the Spirit (Matt. 1:18) to be born in the flesh (John 1:14), the Spirit would never deny that He has come in the flesh through divine conception.