“There are only four or five items that are recounted in all four gospels. The synoptics - Matthew, Mark, and Luke - tell many of the same things, but John's work seems to be more of a supplement, filling in the gaps, recording events and teachings the other three don't mention. But one of the rare references that all four include goes something like this: ‘There is one coming after me who is much greater than I, the strap of whose sandal I am not worthy to untie. I have baptised you with water, but he will baptise you with the Holy Spirit.’ These words of John the Baptist, or words virtually identical, are found in Matthew 3:11, Mark 1:8, Luke 3:16, and John 1:33. The connotation of being baptised has to do with ‘being immersed in’, or ‘being taken over by’. Jesus used the same expression in reference to the suffering he was to undergo. (Mark 10:38-39) It appears the followers of Jesus were to be overtaken by the Holy Spirit.
“In addition, Jesus himself makes reference to the same thing when, just before he ascended to the Father, he bids the disciples to wait in the city because ‘within a few days you will be baptised with the Holy Spirit.’ (Acts 1:5)
“The best definition of the the experience of being baptised with the Spirit is to be found in a little book by Father Francis Martin. He says the expression is ‘a common way of describing a personal, abiding experience of the reality of the presence of Jesus Christ, manifested in a transformed life and the use of spiritual gifts.’” (Baptism in the Holy Spirit, a Scriptural Foundation, page 1)