Secondly. Next, I shall give you some rational account why Christians should make this the great business of their lives, to keep their hearts.
The importance and necessity of making this our great and main business, will manifestly appear in that, 1. The honour of God; 2. The sincerity of our profession; 3. The beauty of our conversation; 4. The comfort of our souls; 5. The improvement of our graces; and, 6. Our stability in the hour of temptation; are all wrapt up in, and dependent on our sincerity and care in the management in this work.
1. The glory of God is much concerned therein; heart-evils are very provoking evils to the Lord. The schools do well observe, that outward sins are majoris infamae, sins of greater infamy; but heart-sins are majoris reatus, sins of deeper guilt. How severely hath the great God declared his wrath from heaven against heart wickedness; the great crime for which the old world stands indicted, is heart wickedness, Gen. vi. 5, 6, 7. God saw that every imagination (or fiction) of their heart was only evil, and that continually; for which he sent the most dreadful judgment that was ever executed since the world began: And the Lord said I will destroy man whom I have created from the face of the earth, both man and beast, and the creeping things, and the fowls of heaven, for it repenteth me that I have made man, v. 7. We find not their murders, adulteries, blasphemies, (though they were defiled with these) particularly alleged against them; but the evils of their hearts: yea, that which God was so provoked by, as to give up his peculiar inheritance into the enemy’s hand, was the evil of their hearts, Jer. iv. 14. O Jerusalem, wash thine heart from wickedness, that thou mayest be saved; how long shall vain thoughts lodge within thee? The wickedness and vanity of their thoughts God took special notice of; and, because of this, the Chaldean must come upon them as a lion from his thicket, and tear them to pieces, v. 7. For the very sin of thoughts it was that God threw down the fallen angels from heaven, and keeps them still in everlasting chains to the judgment of the great day; by which expression is not obscurely intimated some extraordinary judgment to which they are reserved, as prisoners that have most irons laid upon them, may be supposed to be the greatest malefactors: and what was their sin? Why only spiritual wickedness. For they having no bodily organs, could act nothing externally against God. Yea, mere heart-evils are so provoking, that for them he rejects with indignation all the duties that some men perform unto him, Isa. lxvi. 3. He that killeth an ox, is as if he slew a man; he that sacrificeth a lamb, as if he cut off a dog’s neck; he that offereth an oblation, as if he offered swine’s blood; he that burneth incense, as if he blessed an idol. In what words could the abhorrence of a creature’s actions be more fully expressed by the holy God? Murder and idolatry are not more vile in his account, than their sacrifices, though materially such as himself appointed: and what made them so? The following words inform us, their soul delighteth in their abomination.
To conclude, such is the vileness of mere heart-sins, that the scriptures sometimes intimate the difficulty of pardon for them. So in the case of Simon Magus, Acts viii. 21, his heart was not right, he had vile thoughts of God and the things of God: the Apostle bids him repent and pray, if perhaps the thoughts of his heart might be forgiven him. O then never slight heart-evils! for by these God is highly wronged and provoked; and for this reason let every Christian make it his work to keep his heart with all diligence.
2. The sincerity of our profession much depends upon the care and conscience we have in keeping our hearts; for it is most certain, that a man is but an hypocrite in his profession, how curious soever he be in the externals of religion, that is heedless and careless of the frame of his heart: you have a pregnant instance of this in the case of Jehu, but Jehu took no heed to walk in the ways of the Lord God of Israel with his heart, 2 Kings x. 31. That context gives an account of the great service performed by Jehu against the house of Ahab and Baal, as also of a great temporal reward given him by God for that service, even that his children to the fourth generation, should sit upon the throne of Israel. And yet in these words Jehu is censured for an hypocrite: though God approved, and rewarded the work, yet he abhorred and rejected the person that did it as hypocritical: and wherein lay his hypocrisy? but in this, that he took no heed to walk in the ways of the Lord with his heart, i. e. he did all insincerely and for self-ends: and though the work he did was materially good, yet he, not purging his heart from those unworthy self-designs in doing it, was an hypocrite: and Simon, of whom we spake before, tho’ he appeared such a person that the Apostle could not regularly refuse him; yet his hypocrisy was quickly discovered: and what discovered it but this, that though he professed and associated himself with the saints, yet he was a stranger to the mortification of heart-sins! Thy heart is not right with God, Acts viii. 21. It is true, there is a great difference among Christians themselves, in their diligence and dexterity about heart-work; some are more conversant and successful in it than others are; but he that takes no heed to his heart, he that is not careful to order it aright before God, is but a hypocrite. And they came unto me as the people cometh, and sit before thee (as my people) and hear thy words, but they will not do them; for with their mouths they shew much love, but their heart goes after their covetousness, Ezek. xxxiii. 31, 32. Here were a company of formal hypocrites, as is evident by that expression (as my people) like them, but not of them. And what made them so? Their outside was fair; here were reverend postures, high professions, much seeming joy and delight in ordinances; thou art to them as a lovely song; yea, but for all that they kept not their hearts with God in those duties, their hearts were commanded by their lusts, they went after their covetousness; had they kept their hearts with God, all had been well; but not regarding which way their hearts went in duty, there lay the core of their hypocrisy.