The Trinity in One verse: John 15:26

I am constantly bewildered by the hermeneutic of Arians, Sabellians, and Macedonians. They strain through the most bizarre contortions to avoid the assertions of Scripture regarding the Godhead, to keep their particular doctrines, their raison-d'etre.

Consider this verse (John 15:26): "When the Helper comes, whom I will send to you from the Father, the Spirit of truth, who proceeds from the Father, He will bear witness about Me."

What do we see here? We see three distinct entities, the Helper/Spirit, Jesus, and the Father. The Spirit will come to bear witness about the Son. Thus, He is a Person, not an impersonal force, as the Arians and Macedonians claim. Also, He proceeds from the Father and is sent by the Son, distinct actions by discrete Persons, contrary to the assertion of the Sabellians that all three names refer to the same Person. 

I certainly grant that this one verse doesn't address every element of the Trinity. However, it does address and refute some of the specific assertions of the anti-Trinitarians.