WCF 14.3.
This faith is different in degrees, weak or strong; (Heb. 5:13–14, Rom. 4:19–20, Matt. 6:30, Matt. 8:10) may be often and many ways assailed, and weakened, but gets the victory: (Luke 22:31–32, Eph. 6:16, 1 John 5:4–5) growing up in many to the attainment of a full assurance, through Christ, (Heb. 6:11–12, Heb. 10:22) who is both the author and finisher of our faith. (Heb. 12:2)