I didn't recognize him, but he who sent me to baptize in water, he said to me, 'On whomever you will see the Spirit descending, and remaining on him, the same is he who baptizes in the Holy Spirit.'

 John says that he did not know Jesus. Now John was a relation of Jesus ( Luke 1:36), and he must have been acquainted with him. What John is saying is not that he did not know who Jesus was, but that he did not know what Jesus was. It had suddenly been revealed to him that Jesus was none other than the Son of God. 