'Blood' in the Bible

but if we [really] walk in the Light [that is, live each and every day in conformity with the precepts of God], as He Himself is in the Light, we have [true, unbroken] fellowship with one another [He with us, and we with Him], and the blood of Jesus His Son cleanses us from all sin [by erasing the stain of sin, keeping us cleansed from sin in all its forms and manifestations].

This is He who came through water and blood [His baptism and death], Jesus Christ—not by the water only, but by the water and the blood. It is the [Holy] Spirit who testifies, because the Spirit is the truth. [He is the essence and origin of truth itself.]

the Spirit and the water and the blood; and these three are in agreement [their testimony is perfectly consistent].