Roman Catechism 10.31

Chapter 10 — Part I: The Creed — Article VIII: I Believe in the Holy Ghost

Section 31. Justifying Grace — But the grace of justification, which signs us with the Holy Spirit of promise, who is the pledge of our inheritance,' transcends all His other most ample gifts. It unites us to God in the closest bonds of love, lights up within us the sacred flame of piety, forms us to newness of life, renders us partakers of the divine nature, and enables us to be called and really to be the sons of God.