You have seen that the keeping of the heart is the great work of a Christian, in which the very soul and life of religion consists, and without which all other duties are of no value in the sight of God. Hence, to the consternation of hypocrites and formal professors, I infer:
1 That the pains and labors which many persons have undergone in religion are of no value, and will turn to no good account. Many splendid services have been performed by men, which God will utterly reject: they will not stand on record in order to an eternal acceptance, because the performers took no heed to keep their hearts with God. This is that fatal rock on which thousands of vain professors dash and ruin themselves eternally; they are exact about the externals of religion, but regardless of their hearts. O how many hours have some professors spent in hearing, praying, reading and conferring! and yet, as to the main end of religion, they might as well have sat still and done nothing, the great work, I mean heart-work, being all the while neglected. Tell me, vain professor, when did you shed a tear for the deadness, hardness, unbelief or earthliness of your heart? And do you think your easy religion can save you? If so, you must invert Christ’s words, and say, Wide is the gate and broad is the way that leadeth to life, and many there be that go in thereat! Hear me, ye self-deluding hypocrite; you who have put off God with heartless duties; you who have acted in religion as if you had been blessing an idol; you who could not search your heart, and regulate it, and exercise it in your performances; how will you abide the coming of the Lord? how will you hold up your head before him, when he shall say. ‘O you dissembling, false-hearted man! how could you profess religion? with what face could you so often tell me that you loved me, when you knew in your conscience that your heart was not with me?’ O tremble to think what a fearful judgment it is to be given over to a heedless and careless heart, and then to have religious duties instead of a rattle to quiet and still the conscience!
2 I infer for their humiliation, that unless the people of God spend more time and pains about their hearts than they ordinarily do, they are never like to do God much service, or to possess much comfort in this world. I may say of that Christian who is remiss and careless in keeping his heart, as Jacob said of Reuben, Thou shalt not excel. It grieves me to see how many Christians there are who live at a poor, low rate, both of service and comfort, and who go up and down dejected and complaining. But how can they expect it should be otherwise, while they live so carelessly?
O how little of their time is spent in the closet, in searching, humbling, and quickening their hearts!
Christian, you say your heart is dead, and do you wonder that it is, so long as you keep it not with the fountain of life? If your body had been dieted as your soul has, that would have been dead too. And you may never expect that your heart will be in a better state until you take more pains with it.