Final answer:
John was told that the individual upon whom the Spirit descended and remained is the one who baptizes with the Holy Spirit, marking Jesus as the Messiah.
Step-by-step explanation:
John was told that the One upon whom he saw the Spirit descending and remaining on Him was the One who baptizes with the Holy Spirit. This event is narrated in the accounts of the Baptism of Christ, where John the Baptist recognizes Jesus as the one who fulfills this role. According to the gospels in the New Testament, specifically in John 1:33, John the Baptist received a revelation that the person upon whom he saw the Spirit come down and remain is the one who baptizes with the Holy Spirit. This identification marks Jesus as the Messiah and the Son of God, who would take on the sins of the world and offer salvation to humanity.