Mark 1:8 “I indeed have baptized you with water: but he shall baptize you with the Holy Ghost.”
These words by John the Baptist are often repeated in the New Testament (Matthew 3:11; Luke 3:16; John 1:26; Acts 1:5). He says that he baptized (immersed) people using water, but that Jesus would baptize (immerse) people using the Holy Spirit. I Corinthians 12:13 is the key verse in the New Testament regarding the baptism of the Holy Spirit. It shows that during this Church Age, the Holy Spirit baptizes all believers into the Church, the Body of Christ. This operation of the Holy Spirit happened for the first time on the day of Pentecost (Acts 2) when the Holy Spirit formed the Church by placing believers into a body. There was no Church in the Old Testament because there was no baptism of the Holy Spirit before Acts 2. As believers, we are in Christ’s body i.e., in Him, in His Church (Romans 6:3; Galatians 3:27). This is a wonderful place to be.