HEART DISEASE

1 Kings 8:38
"which shall know every man the plague of his own heart...then hear thou in heaven, thy dwelling place, and forgive..."

These words are part of the prayer which Solomon offered up to God, at the dedication of the temple. After he had addressed the divine Being, by mentioning several of his attributes, and expressed his admiration that he should dwell upon the earth among men; he requests of God, that not only the present prayers might be graciously answered; but that all the future supplications of the Israelites, whether as a body of people, or individuals, might be regarded. 

In a more particular manner he entreats of the Lord, that when those who shall he be sensible of the plague of their own hearts, and distressed by it, apply to him for relief, that he would hear and forgive.

What is meant by the plague of the heart; and what we may learn from this expression, 'which shall know every man the plague of his own heart'?

...the heart of man is not whole and sound. It is unhealthful; it is distempered; it is attended with a very grievous disease; for what more grievous than the plague? The disease of the heart of man is sin, and particularly indwelling sin; the sin of our nature, which has its seat in the heart. Every sin is a disease, as is clear from what the Psalmist says, Who forgiveth all thine iniquities, and healeth all thy diseases (Ps. 103:3). Here diseases and iniquities are represented as the same; and the healing of these diseases is signified by the forgiveness of iniquity.
Now as every sin is a disease, so more especially indwelling sin, or the sin of our nature. 

For almost six thousand years there has not been one of Adam's posterity that has escaped this disease; except the man Christ Jesus, who descended not from him; by ordinary generation; otherwise, all mankind have been infected with this plague, this pestilential disease, sin. 

All, says the apostle, are under sin. All have sinned, and come short of the glory of God. Now if there were any person free from this infectious disease, sin; undoubtedly the omniscient eye of God would observe it. It is most manifest, then, that there are none of all the individuals of human nature that have escaped it: all are infected with it all; the body, and the members of it: the soul, and all the powers thereof. It may be said, of men in general, as it is of the body of the people of Israel, that the whole head is sick, and the whole heart is faint. It is an epidemical disease.

It is a very nauseous and loathsome disease: the Psalmist speaks of it as such, My loins are filled with a loathsome disease (Ps. 38:7). He had respect to sin, or the fruit, and effect of it; for he had before observed, that there was no soundness in his flesh, nor any rest in his bones, because of his sin (Ps. 38:3). 

This is a disease that mankind are very early infected with; therefore, the apostate sons of Adam are represented by an infant cast out into the open field, to the loathing of its person in the day that it was born. Being infected with such a disease as this, it cannot but be loathsome in the eyes of God: and sin, that makes us loathsome in the sight of God, makes us loathsome in our own sight too, when we are led to take a proper view of it. 

Hence those words of the apostle Paul, who had a large experience of the nature, force, and power of indwelling sin; O wretched man, that I am! who shall deliver me from the body of this death? (Rom. 7:24); or from this dead body, which I carry about with me. Do but represent unto yourselves how loathsome it must be for a living man to have a dead body fastened to him, and be obliged to carry it along with him wherever be goes; and to have it wherever he is. Just so it is with the people of God, who have any knowledge of this pestilential disease, this body of death, which they continually carry about with them.

This is a disease, also, that is mortal in itself, a deadly disease; as the plague is generally supposed to be. There are diseases which are not unto death; but the disease of sin is unto death. We read of one sin in particular which is unto death. It is emphatically so, namely, the unpardonable sin; because it is not forgiven, neither in this world, neither in the world to come (Matthew 12:32). But every sin is, in its own nature, deserving of death. The wages of every sin, is death (Rom. 6:23); eternal death. 

This disease is incurable, except by the grace of God and the blood of Christ.

Excerpts from The Plague of a Man's Own Heart, John Gill