Throughout the Bible, the Holy Spirit is described as having several personal characteristics. While it is true Scripture sometimes personifies things (e.g., "Wisdom" in the Proverbs), this is not the case with the Holy Spirit.
The Spirit is not a thing—He is not a force or power like electricity, as some teach—neither is He merely the power of God, or God's mind, as other anti-trinitarians assert. Rather, the Biblical record clearly shows the Holy Spirit is a Person:
1. The Holy Spirit leads people:
Matt 4:1 (also Mark 1:12; Luke 4:11) - He led Jesus into the wilderness.
John 16:13 - He will guide us "into all the truth."
Acts 8:39 - He "caught Phillip away."
Rom 8:14 - He leads the children of God (cf. Gal 5:18).
2. The Holy Spirit speaks:
Mark 13:11 - "it is not you who speak, but the Holy spirit" (also Matt 10:19,20).
Acts 4:25 - He spoke "by the mouth of David."
Acts 8:29 - He speaks to Phillip.
Acts 11:12 - He told Peter to go with Cornelius' men.
1 John 4:2 - "Spirit of God" known by His confessing that "Christ has come in the flesh."
Rev 2:7,11,7,29; 3:6,13,22 - "... let him hear what the Spirit says to the churches."
Rev 22:17 - "The Spirit and the Bride say, ‘Come!’"
See also: John 16:13-14; Acts 13:2; 1Tim 4:1; Heb 3:7; Rev 14:13; 22:17.
3. The Holy Spirit testifies/ bears witness:
John 15:26; Acts 20:23; Rom 8:16; 1John 5:7,8.
4. The Holy Spirit teaches:
Exod 31:2-4; Neh 9:20; Luke 12:12; John 14:26; 1Cor 2:13.
5. The Holy Spirit helps us in many ways:
John 14:16,17,26; 16:7 - He dwells with us, teaches us, and comes to us.
Rom 8:26 - He "helps in our weaknesses" and "makes intercession for us."
Titus 3:5 - He renews us.
6. The Holy Spirit sanctifies us:
Rom 15:16; 1Cor 6:11; 1Pet 1:2.
7. The Holy Spirit has a mind and can reason:
Acts 15:28 - "it seemed good to us and the Holy Spirit.…"
Rom 8:27 - He has a mind.
1Cor 2:11 - He knows God's thoughts.
8. The Holy Spirit reveals things to us:
Luke 2:26 - He revealed to Simeon he would see the Christ.
John 16:13 - He will disclose to the apostles "things to come."
1Cor 2:10 - God reveals things through the Holy Spirit "for the Spirit searches all things, yes, the deep things of God."
Eph 3:5 - He reveals the mystery of Christ.
1Pet 1:11 - "Spirit of Christ" in the prophets "testified beforehand the sufferings of Christ and the glories that would follow."
9. The Holy Spirit performs works:
John 16:8-11 - He convicts.
Acts 2:4 - He gave the Apostles "utterance."
Acts 13:4 - He "sent out" Barnabas and Saul (cf. v.2).
Acts 16:6,7 - He forbid Paul to go to Asia.
Acts 20:28 - The Holy Spirit "has made you overseers."
1Cor 12:8,9,11 - Gifts given through, by, and "as He wills."
1Cor 12:11 - "the same Spirit works all these things."
1Cor 12:13 - He baptizes us into Christ.
2Cor 3:6 - "the Spirit gives life."
2Cor 3:8 - Paul speaks of "the ministry of the Spirit."
Eph 3:16 - God strengthens us through His Spirit.
1Tim 3:16 - Christ "Justified in [by] the Spirit."
2Tim 1:14 - He helps us guard our faith.
1Pet 3:18 - He makes us alive.
2Pet 1:21 - He guided men to write Scripture/speak from God.
10. Other indications of the Spirit’s personhood:
Gen 1:2 - He "was hovering over the face of the waters" (compare Deut 32:11).
Gen 6:3 - He strives with sinners.
Ps 51:11; 139:7 - Indicate His personality (in their contexts).
Isa 48:13 - He can be informed, as by a counselor.
Matt 1:18, 28 - Jesus conceived by the Spirit (also Luke 1:35).
Matt 12:31-32 - He can be blasphemed (also Luke 12:18).
Luke 2:25-27 - Simeon "came by the Spirit into the temple."
John 3:5,6,8 - People are "born of the Spirit."
Acts 5:3,4 - He can be lied to.
Acts 7:51 - He can be resisted.
Acts 13:2 - He uses the first-Person pronouns "Me" and "I."
Acts 21:4 - Disciples speak to Paul "through the Spirit."
2Cor 13:14 - "communion (or fellowship) of the Holy Spirit" (also Phil 2:1).
Eph 4:39 - He can be grieved (also Isa 63:19).
Heb 9:8 - "the Holy Spirit is indicating this."
A key text in understanding that the Holy Spirit is a Person, is John 14:16, where Jesus promises to send "another Helper (or Comforter)" to His disciples. These two words - "another" and "Helper" - clearly prove the Spirit is indeed a Person.
The Greek word translated "another" (allos), means "another of the same kind."1 Thus, if we believe Jesus to be a Person (and, for that matter, to be God), then we must believe the Spirit, too, is a Person, and that He is God. To believe otherwise is to make Jesus Christ a mere "power" or "force"— which is obviously false.
As a side-note, Jesus' use of the adjective, "another" clearly demonstrates the Holy Spirit is distinct from the Father and the Son, thus providing support for the doctrine of the Trinity.
Further, the word translated "Helper" (parakletos), includes the idea of "one called alongside to help."2 Surely this indicates another Person called upon for aid, and not some thing!