Behold, I was shapen in iniquity; and in sin did my mother conceive me [Ps. 51:5].
David, as well as the rest of us, came into the world with a sin nature. Paul, recognizing this, says to believers today, “Brethren, if a [Christian] man be overtaken in a fault, ye which are spiritual, restore such an one in the spirit of meekness; considering thyself, lest thou also be tempted” (Gal. 6:1). And Goethe said that he saw no fault committed which he too might not have committed. And Samuel Johnson said, “Every man knows that of himself which he dares not tell his dearest friend.” Even Seneca, a pagan philosopher of Rome, said, “We must say of ourselves that we are evil, have been evil, and unhappily, I must add—shall be also in the future. Nobody can deliver himself; someone must stretch out a hand to lift him up.” And the Word of God confirms this. Even the writer of Ecclesiastes says, “For there is not a just man upon earth, that doeth good, and sinneth not” (Eccl. 7:20). Also in the Book of Proverbs we read, “There is a generation that are pure in their own eyes, and yet is not washed from their filthiness” (Prov. 30:12). There are people who think they are all right, but they are not sensitive to sin. They are like the man in the far North who, as he got colder, wanted to rest. He felt very comfortable sitting down. But those with him knew what was happening to him—he was freezing to death. They wouldn’t let him sit down but kept him moving so he would not die. Today there are many sitting in our churches so cold and so comfortable that they do not realize that in God’s sight they are sinners. We not only need a Savior, but we need cleansing. Paul says, “For I know that in me (that is, in my flesh,) dwelleth no good thing …” (Rom. 7:18). David, you see, went right down to the root of the matter. He confessed that he had a sin nature.
McGee, J. Vernon: Thru the Bible Commentary. electronic ed. Nashville : Thomas Nelson, 1997, c1981, S. 2:764