Listen, Israel! The Eternal is our True God—He alone.
You should love Him, your True God, with all your heart and soul [mind], with every ounce of your strength. Make the things I’m commanding you today part of who you are. Repeat them to your children. Talk about them when you’re sitting together in your home and when you’re walking together down the road. Make them the last thing you talk about before you go to bed and the first thing you talk about the next morning.
Do whatever it takes to remember them: tie a reminder on your hand and bind a reminder on your forehead where you’ll see it all the time, such as on the doorpost where you cross the threshold or on the city gate. [Deut. 4 The Voice]
People are forgetful, so we must be reminded constantly of Wisdom and her ways. We don’t always need to hear something new; often we just need to be reminded of what is true. …wisdom is found when one not only knows what is right, but acts on that knowledge. Foolishness, on the other hand, means a lack of understanding and wrongdoing. – Voice Commentary
Neglecting to teach children about the One True God ensures an increasingly secularized society will teach them about their many gods (which they have no misgiving in doing).