The BAPTISM in the SPIRIT is to receive the Spirit UPON. In Acts, new believers normally received this Baptism soon after their salvation. The PURPOSE of the Baptism in the Spirit is to EMPOWER us to fulfil the Great Commission (Acts 1:8). As well as (1) having the Spirit WITHIN for our own blessing and walk with God (HOLINESS), we also need (2) the POWER of His Spirit, through His Spirit UPON us, to communicate His life and blessing to others. This 2-fold BLESSING of the SPIRIT corresponds to the 2-fold BLESSING of Abraham (Gen 12:2). The Baptism in the Spirit empowers us to be a blessing to others, especially by sharing the Gospel with them, so they can be saved. This 2-fold ministry of the SPIRIT in the New Covenant was prophesied in the Old Testament (Ezek 36:26-27, Joel 2:28-29). The promise of the Baptism in the Spirit (Matt 3:11) came to pass on the Day of Pentecost (Acts 1:5). The life of Jesus, our example and representative reveals this 2-fold experience of the Spirit: (1) He had the Spirit WITHIN Him from birth, and lived a perfectly holy life, even before (2) He was BAPTISED in the Spirit at 30, when He received the Spirit UPON to supernaturally EMPOWER Him for His ministry to others (Luke 3:21-22, John 1:32-33, 2:11, 4:18). When we are born again, we have the SPIRIT WITHIN, but we also need to receive the SPIRIT UPON to empower us to witness and minister to others. Jesus baptises us in the Spirit - the Spirit UPON us (John 1:33). In His teaching, He described these 2 experiences of the Spirit in terms of living water: (1) A Fountain of living water within (John 4:10-14), and (2) Rivers of living water flowing out of us (John 7:37-39).
The apostles also had this 2-fold experience (receiving) of the Spirit: (1) They were BORN AGAIN and received the SPIRIT WITHIN on the day of the resurrection (John 20:22, Gen 2:7). Then Christ prepared them to receive the Baptism in the Spirit (Luke 24:48-49, Acts 1:4-5,8). Then (2) they were baptised in the Spirit at Pentecost, when He came UPON them (Acts 2:1-4). There were 2 aspects to their experience of being baptised in the Spirit: (1) The Spirit came UPON them (v3), and (2) He filled their souls from within (v4). To be filled with the Spirit and so receive the Spirit UPON, we must surrender our soul and body to God to do His will and fulfil His mission. Moreover, God wants us to stay continually filled with the Spirit (Eph 5:18). By surrendering our souls to God and yielding our bodies to Him (by speaking out the words the Spirit gives us), we allow the Spirit to fill our souls from within, and to come UPON us. The outward evidence the Spirit has filled us and has now come upon us, is that we have yielded our tongue to His control by speaking in tongues (v4). Acts 2:4 describes the first time believers received the Baptism in the Spirit, and so it is the prototype description, God’s blueprint for all New Covenant believers. In Acts 11, Peter confirms what they received at Pentecost was the Baptism in the Spirit, because he says what the Gentiles received, when the Spirit came upon them in Acts 10, was the same experience the Jews had ‘at the Beginning’ (Pentecost), which he then described as the Baptism in the Spirit (Acts 11:15-16). Acts 8 describes the 2-stage experience of the Samaritans. They heard the Gospel and were baptised in water, so they were saved (v14,16), but they had not yet received the Spirit upon them (v15-16). When the apostles laid hands on them they received the Spirit upon (v17), which was manifested outwardly in a supernatural way (v18-19), namely by them speaking in tongues (v20).
The 2-Stage experience of the Paul is in Acts 9: (1) He was SAVED when he saw the risen Christ and called him ‘Lord’ (Acts 9:5-6). (2) He was FILLED with the SPIRIT, when Ananias prayed for him 3 days later (Acts 9:9-18), and he spoke in tongues (1Cor 4:18). The Gentile Pentecost is described in Acts 10:44-48 as the Spirit coming upon them, and in 11:15-16 as the Baptism in the Spirit. Just as at Pentecost, the outward evidence of the Baptism was speaking in tongues. This was the only proof the apostles looked for and accepted. Finally, we study the 2-stage experience of the Ephesians in Acts 19. Paul's question in v2 shows that receiving the Baptism in the Spirit is not automatic, when you believe in Christ for salvation. The Ephesians (1) believed the Gospel, that Paul preached to them and were saved (v5a), then they were baptised (v5b), and then (2) "when Paul laid hands on them, the HOLY SPIRIT came UPON them, and they SPOKE with TONGUES and prophesied” (v5c). So, they were BAPTISED in the SPIRIT subsequent to their SALVATION, as a distinct experience. Consistently in Acts, it was normal for Christians to receive the Baptism in the Spirit as a separate experience soon after salvation, and the outward evidence of this Baptism in the Spirit is speaking in tongues.