The prophets contain a clear and repeated promise that in the end God himself will pour out his Spirit on his people (Isaiah 32:15; Isaiah 44:3; Joel 2:28–29; Ezekiel 36:26–27; Ezekiel 37:14; Zechariah 12:10). The stronger one comes to carry out this promise. The verb “pour out” or “lay on” is, however, in this context replaced with “baptize” because of the parallelism with what John does. That can hardly mean “wash” here (John also did not “wash” people in the Jordan), but must refer to the act of immersion and causing someone to be submerged. When God gives his Spirit, the sins are forgiven and they are overcome. He who comes must be divine to be able to bestow the Spirit.1
8 I have baptized you with water, but he will baptize you with the Holy Spirit.”