The New Testament frequently speaks of “the Spirit” along with God the Father and the Lord Jesus Christ. The Spirit is often spoken of literally as “the Spirit, the Holy One,” the One whom we most often call the Holy Spirit (e.g. Luke 4:1).
As His name suggests, the Holy Spirit is a spirit (Greek pneuma or pneumatos). This means that we cannot imagine the Spirit as having a physical body or any such thing. While many throughout time have thought of the Spirit as an impersonal force or entity, He is revealed in the Scriptures to have personality and consciousness. The Holy Spirit is called the Comforter (Greek parakletos, John 14:16-17); He has a mind (Romans 8:27), communicates (e.g. Acts 10:19), makes intercession before God (Romans 8:26), and can be grieved (Ephesians 4:30). The Holy Spirit maintains full personhood and therefore has personality just as the Father and the Son. As the Father and the Son, the Holy Spirit is spoken of and envisioned as masculine; as spirit like the Father, He likely maintains both “masculine” and “feminine” characteristics (Genesis 1:26-27, Luke 4:1, John 14:16-17).
Christians believe the Holy Spirit is the third person of the Godhead along with the Father and the Son. During the creation, the Spirit hovered over the waters (Genesis 1:2); when Jesus was baptized, the Spirit descended upon Him as a dove (Matthew 3:16, Mark 1:10, Luke 3:27, John 1:32-33). Paul calls the Spirit the Lord in 2 Corinthians 3:17 and prays that Christians might be in the communion of the Spirit in 2 Corinthians 13:14. Peter associates the Spirit with the Father and Jesus in 1 Peter 1:1-3 and declares that the prophets spoke from God as they were moved by the Holy Spirit (2 Peter 1:21). The Hebrew author quotes Jeremiah 31:33-34 in Hebrews 10:15-17, saying that the Holy Spirit has testified to us with those words; Jeremiah had declared that YHWH, the LORD, had spoken to Him (Jeremiah 31:31). The Holy Spirit is speaking when YHWH speaks; the Holy Spirit is therefore part of YHWH and is God Himself. Since God is one (Deuteronomy 6:4-6, John 17:20-23), it is evident that the Holy Spirit is part of that relational unity within the Godhead, of the same substance, essence, will, purpose, and mind as the Father and the Son.
While the Holy Spirit is God along with the Father and the Son, the Scriptures suggest that the Holy Spirit works entirely at the discretion and direction of the Father and the Son; no human in Scripture speaks specifically to the Spirit or makes any request to Him directly. The Spirit is sent by the Father (John 14:26) or the Son (John 15:26) to accomplish whatever is intended; people make requests of God the Father and He would communicate to them through the Holy Spirit (1 Peter 1:10-12, 2 Peter 1:19-21).
The Spirit is the means by which God has communicated His message, will, and purpose to mankind. The prophets spoke the word of God as prompted by the Spirit (2 Peter 1:21); the Spirit was upon Jesus while He lived on earth (cf. Luke 4:1), and even when Jesus is communicating to His churches, it is done through the Spirit (e.g. Revelation 2:7). The Holy Spirit inspired Peter and the Apostles with the message of the Gospel and its proclamation (John 14:26, 15:26-27, Acts 1:4-5, 2:1-36). The record of these inspired sayings and writings are preserved for us in the Bible.
The Scriptures also declare that the Spirit has a role in sanctification (Romans 15:16, 2 Thessalonians 2:13, 1 Peter 1:2). This is consistent with the description of the Spirit as the “Holy One,” since sanctification involves being holy. Such is why Paul speaks of characteristics like love, joy, peace, and such things as the “fruit of the Spirit” in Galatians 5:22-24 (cf. Colossians 1:8, 1 Thessalonians 1:6), and speaks of the Christian life in terms of being “led by the Spirit” (Romans 8:14, Galatians 5:18) and “walking by the Spirit” (Romans 8:4, Galatians 5:16). The Holy Spirit is also said to make intercession before God for Christians, helping them in their weakness (Romans 8:26-27). Let us thank God for the Holy Spirit and the work He has done on our behalf!