This divine exhortation penetrates to the very core of Christian living. The heart in scripture is not merely the seat of emotion, but the center of a person's being, the mind, will, affections, and conscience. It is from the heart that all of our thoughts arise, all of our choices are made, and all of our desires take shape. Therefore, to guard the heart is to diligently watch over the whole inner man, to protect it from corruption, and to keep it fixed on what is holy and true.

Solomon, under the inspiration of the Spirit, gives this command above all else. This signals its supreme importance. The external life cannot rise above the internal condition. Outward behavior is the fruit, the heart is the root. As Jesus declared, Out of the overflow of the heart, the mouth speaks, If the fountain is polluted, the stream will be defiled. If the heart is impure, so will be the thoughts, words, and actions.

Why must the heart be so closely guarded? Because it is constantly under attack from the world, the flesh, and the devil. Satan knows that if he can gain entrance to the heart, he can influence the whole course of life. Therefore the believer must post a sentinel at every gate. What we see, what we hear, what we dwell upon in secret thought. We must take every thought captive to make it obedient to Christ.

To guard the heart is not a call to stoicism, but to spiritual vigilance. It means treasuring what is pure, meditating on God's Word, delighting in Christ, confessing sin promptly, and depending moment by moment on the power of the Holy Spirit. It is a conscious, continual effort to keep the affections fixed on things above, not on earthly things.

The heart determines the course of your life. This truth lays bare the delusion that sin is only a small matter. Every decision, every habit, every desire shapes the path we walk. If our hearts are filled with the fear of the Lord and love for His truth, then our steps will be firm and straight. But if our hearts are given over to self, then the path will be crooked and dark.

Let us then pray with David, create in me a pure heart, O God, and with all diligence watch over the inner sanctuary of our soul, for from it flow the springs of eternal consequence.