God's Being is not limited only to one personality. The contradiction arises in the conception of the Holy Trinity only if we assume this kind of identity which is used in the objection. I will now explain what is significant in conceiving God as a Perfect Divine Being who manifests own glory in three uncreated persons. The Holy Trinity consists of the Father, the Word and the Holy Spirit. The Father was never seen by any man.
Thoughts are the identity of the existence.
I think therefore I am. God's thoughts are eternal in the virtue of His eternal beingness. In the same manner, the Holy Spirit is a Personalization of God's powers and forces, because God's forces have a tremendous creative vitality to sustain themselves independently, and consequently can form their own Personality filled with intelligence, which is namely the personhood of the Holy Spirit. Since divine forces are eternal, so is the Holy Spirit an eternal and integral Person of God's Being. In the biblical conception of God there is not assumed that one Being is identified with one personality.