1 John 5:6-8

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