So there are three who testify, the Spirit, the water, and the Blood, and the three are of one accord. To understand this rather odd statement in St. John’s first epistle we must look at the historical context. By the end of the first century, sixty or so years after Jesus’ death when this epistle was written, there were already great disputes about his nature and identity. How could a human being be the son of God? St. John’s response to these disputes is to insist on what we call the incarnation, that Jesus had both a 100% a human nature and a 100% divine nature. So, yes, the Spirit testifies to Jesus as the son of God come into the world. But the water does as well — Jesus was a human being who lived under the law as a pious Jew even undegoing baptism right to the end of his life when the blood testified to his complete dedication to doing the will of God. To understand Jesus you must see him in his totality.
