In making this claim, Lombard pushed to the extreme the anti-Pelagian logic of Augustine. Saint Thomas rejected this Lombardian theory and Trent followed him. We cannot identify charity with the Holy Spirit because it leads to pantheism, like putting a drop of whisky in the ocean. If charity is identified with the Holy Spirit, then the Holy Spirit forces action in us, and we are puppets. The supernatural gifts are created, not identified with God though they come from God.
Grace is a new qualification of our inner being.
It is not identical with God. So Saint Thomas's definition is personalistic and dynamic. We are not united hypostatically like Christ, not does Saint Thomas reify grace. We are elevated to a new status, but we experience it as something that is our own. To be divine, our action must also be fully human.