Answer: God gave the Bible to teach us about Himself and to show us how to live.
The heart is a mysterious thing. Not just the muscle and arteries and chambers parts of it. It’s fascinating enough to examine and marvel at God’s ways of creation. But the heart, as described by Scripture, is truly a mysterious thing, for, as Jeremiah said, “Who can know it?” (Jer. 17:9b)
It holds the wellspring of life, and must be guarded above all else (Proverbs 4:23) by the peace of God (Philippians 4:7).
A pure heart must be created anew by God, accompanied by a steadfast spirit (Psalm 51:10).
Even when the heart of flesh fails, God Himself is the strength of a spiritual heart (Psalm 73:26).
The desires of my heart are directly related to my delight in the Lord (Psalm 37:4).
The pure in heart are blessed, and as such, will see God (Matthew 5:8).
When we teach the lessons of the catechism to children, we know we’re not doing so in a vacuum. There are countless levels of application the Lord will provide for us – all of us, from the children to the teachers to the parents to the helpers. There are just as many opportunities to meditate on the truths and consider how they fit with the pieces of doctrine and teaching the Lord has us hear from other sources – sermons, books, fellowship and discussion with friends, child training sessions, social media posts, music.
The filter for all of this is the heart. Is my heart prepared to hear what the Lord has to say to me about Himself, what He has done, and how He wants me to live for Him? Or is it opposed to the Bible's teachings and exhortations; the Spirit's prodding, comforts, and rebukes -- even the Gospel message of grace and promise? Is my heart murmuring, fretting, vexing? Does it go about, unfettered, on unstable, disquieted, and tumultuous jaunts? Is it distracted? Is it sinking in disappointment?
Jesus cautioned the worries and cares of this world and its afflictions and distractions can choke out the Word as surely as invasive vines can throttle a plant or journeying roots can undermine a tree. Jeremiah Burroughs says in his classic work, The Rare Jewel of Christian Contentment, “God would have us depend on Him” despite the external events that might cause our hearts to fret or be disquieted. This contentment of the soul governs how we look to His word. How we regard the Bible and its purpose feeds our understanding of whence comes a heart ready to love and trust God.
I must not neglect to consider the matters of the heart when training up my children in the wisdom and knowledge of the Lord, to be attuned to internal rumblings that would oppose what the Lord wants to do or say, not only to me, but to them, as well.