The Holy Spirit is the Spirit of God, first mentioned right in the beginning of creation (Gen 1:2). The Holy Spirit is repeatedly referred to as “He”, a person who does, wants and feels (John 14:17). The Holy Spirit is the Spirit of Christ (Rom 8:9-11). As Christ has gone to heaven, He is there in front of the throne as our defender and intercessor. For us Christ sent His Spirit to stay with us. When Jesus Christ was here on earth in human form, he was limited to one place at each given moment, but his Spirit is not limited in this way. For this reason he said it would be actually our benefit, that he goes away and sends us the Holy Spirit (John 16:7). The Holy Spirit is the second defender (John 14:16), who speaks to our heart and defends the fact of our forgiveness against our thoughts and feelings, while Christ, the first defender, is defending us in front of the Father in heaven where it counts (Rom 8:34).
The Holy Spirit reveals to us our sins and how correct God is in his judgement (John 16:8-13). The Spirit of God is using the Bible as a mirror in front of us, so that we see more about our sinfulness. Only as sinners can we start learning about the love of God towards us. The love of God is focused in the death of Christ for us. The Holy Spirit makes Jesus bright and clear for us (John 16:14-15). Many people have had an experience of the Bible suddenly becoming alive. This is an experience of the Holy Spirit at work. When you feel saddened by your sinfulness or joy because of Jesus, rejoice for the Holy Spirit of God is then in you.