Is it a worthwhile pursuit to memorize scripture? Is this something important we can teach our children? Will this discipline offer rewards that last a lifetime? John Piper presents convincing argument regarding why it is so important to memorize scripture. First, he quotes from the masters:
"Chuck Swindoll wrote, "I know of no other single practice in the Christian life more rewarding, practically speaking, than memorizing Scripture... No other single exercise pays greater spiritual dividends! Your prayer life will be strengthened. Your witnessing will be sharper and much more effective. Your attitudes and outlook will begin to change. Your mind will become alert and observant. Your confidenc and assurance will be enhanced. Your faith will be solidified" (Growing Strong in the Seasons of Life [Grand Rapids: Zondervan, 1994], p. 61)."
Next, he gleans from scripture (quoted from source linked below):
1. Conformity to Christ
Paul wrote that "we all... beholding the glory of the Lord, are being transformed into the same image from one degree of glory to another.
1 Samuel 3:21
2. Daily Triumph over Sin
"How can a young man keep his way pure? By guarding it according to your word... I have stored up your word in my heart, that I might not sin against you..."
3. Daily Triumph over Satan
When Jesus was tempted by Satan in the wilderness he recited Scripture from memory and put Satan to flight...
4. Comfort and Counsel for People You Love
The times when people need you to give them comfort and counsel do not always coincide with the times you have your Bible handy. Not only that, the very word of God spoken spontaneously from your heart has unusual power...
5. Communicating the Gospel to Unbelievers
Opportunities to share the gospel come when we do not have the Bible in hand. Actual verses of the Bible have their own penetrating power. And when they come from our heart, as well as from the Book, the witness is given that they are precious enough to learn. We should all be able to sum up the gospel under four main headings (1) God's holiness/law/glory; 2) man's sin/rebellion/disobedience; 3) Christ's death for sinners; 4) the free gift of life by faith. Learn a verse or two relating to each of these, and be ready in season and out of season to share them.
6. Communion with God in the Enjoyment of His Person and Ways
The way we commune with (that is, fellowship with) God is by meditating on his attributes and expressing to him our thanks and admiration and love, and seeking his help in living a life that reflects the value of these attributes. Therefore, storing texts in our minds about God helps us relate to him as he really is. For example, imagine being able to call this to mind through the day:
8 The LORD is compassionate and gracious, Slow to anger and abounding in lovingkindness.
9 He will not always strive with us, Nor will He keep His anger forever.
10 He has not dealt with us according to our sins, Nor rewarded us according to our iniquities.
11 For as high as the heavens are above the earth, So great is His lovingkindness toward those who fear Him.
12 As far as the east is from the west, So far has He removed our transgressions from us.
13 Just as a father has compassion on his children, So the LORD has compassion on those who fear Him.
14 For He Himself knows our frame; He is mindful that we are but dust.
Read Why Memorize Scripture? , by John Piper at Bible Study Tools.