The central message of this sermon is that remembering and gratitude are essential aspects of a healthy relationship with God, but they require effort and intentionality to maintain. The speaker argues that humans have a tendency to forget God's benefits and blessings, which can lead to erosion of their faith and sense of duty towards Him. To counteract this, the speaker emphasizes the importance of using reminders, such as written texts, symbols, or personal objects, to recall God's promises and character. The sermon also highlights the need for mental effort and discipline in remembering God's past actions and promises, and encourages listeners to engage in practices like meditation on Scripture to cultivate a deeper understanding and appreciation of God's Word. Ultimately, the speaker is advocating for a conscious and intentional approach to remembering and gratitude as a means of deepening one's relationship with God and living a more obedient and faithful life.