Keep your heart with all vigilance,
for from it flow the springs of life.
When I was in the military, one of the duties assigned to me occasionally was to be on “guard duty.” It was not a difficult task, necessarily. But, usually, it meant being assigned a particular area of the base to watch and protect against those who would harm. It was typically a long, boring shift, and rarely anything interesting to report. Yet, guard the area I must because something might happen.
The same is true for the Christian life, but it carries far more significance. To guard (NIV) or watch over something is an active duty. It isn’t passive. I could not correctly protect the area of the base while asleep (in fact, our supervisors would often check on us to make sure we were not sleeping!). No, it was something that required a great deal of vigilance. Many things compete for the heart and mind of the Christian in this world. There are temptations from without and from within. The Evil One never tires of bothering, harassing, and seeking to destroy the people of God. Solomon, instructing his son about the ways of the world and the life he is entering, tells him to keep, watch, and guard his heart. Why did he not tell him to guard his actions? Precisely because the heart is the source of evil thoughts and actions. It is the heart that is the feeding trough of the soul. It is the heart that defiles a man and makes him unclean. The heart is the source of life, and if not guarded and protected, it will lead to ruin. A few comments:
First, you must guard your heart because it will lead to ruin if you don’t. Modifying behavior is one thing. Tuning our hearts to the things of the Lord is another. People can change their behavior, if even for a season, but to change their hearts is something that only the Spirit of God can do. Only he can soften hearts and turn them into those things that are good and right. You and I cannot change our hearts. We can desire it and should, but we cannot change it alone. To avoid the evils and pitfalls of this life, the Holy Spirit must warm the heart, or it will never change and inevitably lead to ruin.
Second, you must guard your heart after the things of the Lord. It isn’t modification behavior. It is a rapid pursuit of the things of the Lord in order for our minds and hearts to be tuned to Him. The medicine is contained in the Word of God, which is living and active, sharper than any two-edged sword. If you are serious about guarding your heart against the evils of this world, you must be in the Scriptures. You must meditate on them day and night. You must hear them read and preached. It is the Word of God, used by the power of the Spirit of God, that changes the minds and hearts of sinners.