The promise of the Spirit refers to the coming of the Spirit as prophesied by Isaiah (Isaiah 32:14; Isaiah 44:1–5), Ezekiel (Ezekiel 11:18–19; Ezekiel 36:26–27), and Joel (Joel 2:28–32).1 His presence amongst Jew (Acts 2:1–47) and Gentiles (Acts 10:44–48) is a confirmation that we are living in the new covenant where God’s Spirit is at work in a greater manner than he was before. Since the Spirit is the one who works a true faith in the hearts of God’s people (Acts 16:14; Romans 1:16; Romans 10:17; 1 Corinthians 1:21),2 his presence is closely connected with justification by faith. Indeed, Paul considers the coming of the Spirit and justification by faith to be synonymous.3
14 so that in Christ Jesus the blessing of Abraham might come to the Gentiles, so that we might receive the promised Spirit through faith.