Did John the Baptist know who Jesus was before he baptised him?

‘I knew him not’ need not mean that John had no idea who Jesus was. John is explaining why his witness can be trusted: it did not rest on family ties or his own impressions, but on a sign God had given him beforehand: “Upon whom thou shalt see the Spirit descending, and remaining on him, the same is he” (John 1:33). The Greek, kagō ouk ēdein auton, is emphatic, ‘I myself did not know him’: left to himself, John could not have been sure that this was the Messiah. He uses the same verb a few verses earlier when he tells the crowd, “there standeth one among you, whom ye know not” (John 1:26). They had seen Jesus; they did not know who he was.

The two men were related (Luke 1:36), but they may never have met. John grew up “in the deserts till the day of his shewing unto Israel” (Luke 1:80), and Jesus at Nazareth in Galilee; Gill and Barnes both think the baptism was their first meeting. When Jesus came, John sensed at once that he was holier than himself, whether from what he knew of the family’s story, from Jesus’ bearing, or from God’s prompting, much as Samuel was told which of Jesse’s sons to anoint when David came in (1 Samuel 16:12). So he protested, “I have need to be baptized of thee” (Matthew 3:14). The sign at the baptism then made it certain. As Barnes puts it, John may have had some intimation before, but by the sign he would know it beyond doubt.

Not known as the Messiah

Many read John’s words as ‘I did not know him as the Messiah’, whether or not he had met Jesus before. On this view John knew Jesus as a relative and a righteous man, which explains his reluctance in Matthew 3:14, and the sign showed him that Jesus was the Christ.