Because of the fall into sin, our brains have significant weaknesses. For the issue of sanctification, none is more damaging than our tendency to forget the good things we’ve learned. Constant repetition is necessary to keep past scriptural truth always in the forefront of our minds. It is not the case that every time we read the Bible or hear a good sermon we learn something entirely new, nor is that necessary. Sometimes, all that’s required is to be reminded of past insights. Paul said that constant reminders acted as a “safeguard” for Christians (Philippians 3:1), and Peter made reminding his disciples of past truths in which they were well- established a centerpiece of his ministry (2 Peter 1:12–13). This is especially true in the issue of the fundamental, central facts of the gospel itself, which we will never outgrow.
Dr. Andrew Davis, An Infinite Journey