There is all the difference in the world between the ways in which the answer to this question is spoken; and there is only one way, only one meaning, in which it can be spoken honestly, as before God, from the ground of the heart.
I. There is, for instance, the careless, indifferent, frivolous answer, the answer of those who have hitherto resisted the grace of God, and who, finding that they can sin as yet with but little sorrow, neither know nor really care what religion means. "Is my heart right? Yes, I suppose so. If I am not particularly good, I am not particularly bad," and so on. Such an answer means nothing, or worse than nothing. In your "Yes" God reads "No." In your "My heart is right" He reads that it is "deceitful above all things and desperately wicked."
II. Take another answer, not, like the last, wholly hollow and insincere, but too impulsive, too confident. "Is thine heart right?" "Yes," another will say. "I do sincerely dislike what is bad, and I despise myself for the weakness with which I yielded to it. And I mean to be quite different now." This answer involves, not merely a weak wish, but a strong desire; not only a strong desire, but a resolute effort; not only even a resolute effort, but an intense and absorbing passion. A weak resolve, a half-resolve, a mere verbal resolve, a resolve made in your own strength of what use is it? There is a deep-sighted proverb which says, "Hell is paved with good intentions."
III. "Is thine heart right?" Take one more answer. Some may answer carelessly, some presumptuously, but will not many answer in a deeper, humbler, sincerer, more serious spirit? "Though my life has not been always right," you will say, "yet I hope, I trust, that my heart is right. It is not hard. My own strength is weakness, my own righteousness is utter sin, but I lift up mine eyes unto the hills, whence cometh my help." "Make me to do the thing that pleaseth Thee, for Thou art my God. Let Thy loving Spirit lead me into the land of uprightness."
F. W. Farrar, In the Days of thy Youth,p. 179.
References: 2 Kings 10:15. S. Baring-Gould, One Hundred Sermon Sketches,p. 161. 2 Kings 10:15; 2 Kings 10:16. A. Edersheim, Elisha the Prophet,p. 298.