Whatever the immediate cause, we see the result in Proverbs 4:23. Guard your heart. Above anything else, be discerning and careful with your heart. Do not easily let anyone into your heart, do not readily allow another to guide your heart.
Because from the overflow of the heart, the mouth speaks and the body acts. What is inside of us is what comes out into our life, into our action.
If we are going to have lives that reflect the glory of God, then our hearts must be focused on His glory, His ways. If not, we are in trouble. There are two ways our hearts get us into trouble.
The first is their natural tendency to drift. Easily, too easily, we turn to golden calves and lesser desires. We choose the quicker paths and the more fleshly fulfillments. This is why so much about the sins that have entangled us is a life of ease. We will trade a big pleasure later for a small pleasure and a big pain later. That is the state of the heart left alone.
Think about it: why are drugs a problem? Sex? Any other form of moral or ethical lapse? We would rather shoot up or sex up or corrupt our way to what we want than work for it. After all, a body that feels good is good enough, why work for a body in good shape? A quick night that meets the urges is easier than a lifelong commitment, so why marry? And if I can take what I want instead of earning it, then I’ll have it—you probably have enough, anyway.
Our hearts drift this way, and that is the bigger danger here. We must guard our hearts from drift by constantly being renewing our minds in Christ. By constantly pouring in the Word of God—because we leak. (It is worth noting that between Hebrew culture and Greco-Roman culture, the heart/mind/soul/emotion/thought distinction is not as solid as it is in modern America, nor as localized. Mind and heart are not as separate as we make them.)
Our hearts can also be drawn astray by others. I know this danger, and have succumbed to it. Yet this is not the greatest danger we see—readily there are those to warn us and guard us. It from within that danger rises up.
Defeat it—or 300 porcupines will seem like an easy problem.