(JOHN 15:26) "But when the Comforter is come, whom I will send unto you from the Father, even the Spirit of Truth, which proceedeth from the Father, he shall testify of me".

COMFORTER is the HOLY GHOST

TESTIFY comes from TESTAMENT

TESTAMENT means 3RD PERSON standing by

ROOT word is tri-st-i which means THREE

TRINITY: FATHER, SON, HOLY GHOST