With the resurrection of the Christ the mystery of life after death became a lot less mysterious. It moved from the realm of conjecture and fantasy to a reality grounded in (of all things!) our human bodies
The one who believes has the Spirit, the water, and the blood literally within himself, bearing witness to the individual that Jesus is the risen and ruling savior of the world.
The hallmark of the Spirit of truth is that Jesus Christ, true Son of God, and true Son of Mary, “for us men and for our salvation,” came in the flesh.