Pink on Spiritual and Natural Ability

"But now the question returns, How can God hold the sinner responsible for failing to do what he is unable to do? This necessitates a careful definition of terms. Just what is meant by "unable" and "cannot"?
Now let it be clearly understood that when we speak of the sinner's inability, we do not mean that if men desired to come to Christ they lack the necessary power to carry out their desire. No; the fact is that the sinner's inability or absence of power is itself due to lack of willingness to come to Christ, and this lack of willingness is the fruit of a depraved heart. It is of first importance that we distinguish between natural inability and moral and spiritual inability. For example, we read, "But Ahijah could not see; for his eyes were set by reason of his age" (1 Kings 14:4); and again, "The men rowed hard to bring it to the land; but they could not: for the sea wrought, and was tempestuous against them" (Jonah 1:13). In both of these passages the words "could not" refer to natural inability. But when we read, "And when his brethren saw that their father loved him (Joseph) more than all his brethren, they hated him, and could not speak peaceably unto him" (Gen. 37:4), it is clearly moral inability that is in view. They did not lack the natural ability to "speak peaceably unto him" for they were not dumb. Why then was it that they "could not speak peaceably unto him"? The answer is given in the same verse: it was because "they hated him." Again; in 2 Peter 2:14 we read of a certain class of wicked men "having eyes full of adultery, and that cannot cease from sin." Here again it is moral inability that is in view. Why is it that these men "cannot cease from sin"? The answer is, Because their eyes were full of adultery. So of Romans 8:8-"They that are in the flesh cannot please God": here is spiritual inability. Why is it that the natural man "cannot please God"? Because he is "alienated from the life of God" (Eph. 4:18). No man can choose that from which his heart is averse-"O generation of vipers, how can ye, being evil, speak good things?" (Matt. 12:34). "No man can come to Me, except the Father which hath sent Me draw him" (John 6:44). Here again it is moral and spiritual inability which is before us. Why is it the sinner cannot come to Christ unless he is "drawn"? The answer is, Because his wicked heart loves sin and hates Christ.

...

Should some sinner here object, I cannot help being born into this world with a depraved heart and therefore I am not responsible for my moral and spiritual inability which accrue from it, the reply would be, Responsibility and Culpability He in the indulgence of the depraved propensities, the free indulgence, for God does not force any to sin. Men might pity me but they certainly would not excuse me if I gave vent to a fiery temper and then sought to extenuate myself on the ground of having inherited that temper from my parents. Their own common sense is sufficient to guide their judgment in such a case as this. They would argue I was responsible to restrain my temper. Why then cavil against this same principle in the case supposed above? "Out of thine own mouth will I judge thee thou wicked servant" surely applies here! What would the reader say to a man who had robbed him and who later argued in defense, "I cannot help being a thief, that is my nature"? Surely the reply would be, Then the penitentiary is the proper place for that man. What then shall be said to the one who argues that he cannot help following the bent of his sinful heart? Surely, that the Lake of Fire is where such an one must go. Did ever a murderer plead that he hated his victim so much that he could not go near him without slaying him. Would not that only magnify the enormity of his crime! Then what of the one who loves sin so much that he is at 'enmity against God'!" - Arthur Pink "The Sovereignty of God"