John didn't say that, Christ Jesus (the Alpha and Omega) did. Christ knew they would add to what He taught the Apostles to lay as the Foundation for His Congregation.
That is, those who were to add to the Scriptures men's doctrines and traditions.
So, Jesus lied when He said God is a Spirit? And "holy" means "separate" from all things. What separates God from all things is, for instance, He is the Creator, and He is without sin.
The Romish church made up a lot of things, but the Holy Spirit isn't one of them.
Certainly God has completely free will to carry out that will. No one stops God, that's why God wins.