Before one can answer that question; it is of prime importance we should seek to ascertain exactly what is connoted by “an honest and good heart” (Luke 8:15), and diligently search ourselves whether or not we possess such.
Clearly the terms used here by Christ (in Luke 8:15) are in designed contrast from Jeremiah 17:9—“the heart is deceitful above all things and desperately wicked,” which describes that which every descendant of Adam is born with.
“An honest and good heart” then is not the natural heart, but one which Divine grace has imparted.
“The preparation (or disposing) of the heart in man...is from the LORD” (Prov. 16:1). It is by the regenerative operations of the Holy Spirit that the heart is made honest. Honesty of heart is the grand distinction between the genuine Christian and all other men. We do not regard it as a separate grace, like purity or humility, but rather is the regulator of all the graces: thus we read of “unfeigned faith” (2 Tim. 1:5) and “unfeigned love” (1 Peter 1:22).
As holiness is the glory of all the Divine perfections, so honesty is what gives colour and beauty to all the Christian’s graces. Holiness is the distinctive glory of the Godhead: as Howe termed it, “an attribute of attributes, casting lustre upon the others.” “As God’s power is the strength of His perfections, so His holiness is the beauty of them: as all would be weak without almightiness to back them, so all would be uncomely without holiness to adorn them” (Charnock). This it is on a lower plane: without honesty to regulate them, the graces of the Christian would be worthless.
As honesty of heart is that which distinguishes the genuine Christian from all other men, so it is the grand feature which is common to all the children of God, none of them being without it.
An honest heart is an “upright” heart (Psa. 7:l0); it is a “single” (Col. 3:22) or “undivided” one (Hosea 10:2).
An honest heart is a “sound” one (Prov. 14:30), a “true” one (Heb. 10:22).
The marks and fruits of an honest heart are candor, genuineness, truthfulness, integrity, righteousness, fidelity, sincerity—in contrast from dissimulation, guile, deceitfulness, pretense, treachery. An honest heart hates all shams. But passing from generalizations let us point out some of the more specific and fundamental workings and manifestations of an honest heart.
An honest heart is open to the Word, not merely to certain portions only, but to the Word as a whole. Such an one sincerely wants the Truth, the whole Truth and nothing but the Truth. He does not wish the preacher to please or flatter him, but to be frank and faithful. The language of the unregenerate is, “Speak unto us smooth things, prophesy deceits” (Isa. 30:10). They desire to hear of an easy and flesh-pleasing road to Heaven, one which does not demand the denying of self and forsaking the world. They want to be at ease in their sins and assured they are the children of God while free to serve the Devil. But it is the very opposite with one having an honest heart.
He is fearful of being imposed upon, and thinking more highly of himself than he has a right to do. If he is deceived, he ardently longs to be undeceived; if he is building his house upon sand, he wants to know it. He is willing to be tested and searched, and therefore he “cometh to the Light”—does so repeatedly and continuously, as the tense of the verb denotes. An honest heart, then, is a Truth-loving heart, one which genuinely desires to know the mind of God, one which is ready for his creed, his character and his conduct to be searched by the light of the Sanctuary.
He wants to know the truth about God, the One with whom he has to do, the One before whom he must yet appear and render an account. He will not be put off with any superficial and sentimental representations of the Divine Character, he determines at all costs to acquaint himself with God as He actually is. He wants to know the truth about himself, whether his soul be only slightly disposed or whether his case be so desperate as to be altogether beyond help. He is anxious to determine whether he has only a head or intellectual knowledge of things that matter most or whether he has been given a heart or spiritual knowledge of them. He wants to make certain of how he stands with regard to God and eternity, and he dare not take any man’s opinion or say-so with regard thereto.