Some additional interesting observations from the Professor of Christian Theology at Andover Theological Seminary (long ago, before they went liberal).
"This leads me to say, that the necessity of regeneration, as asserted by our Saviour, (John iii,) is an obvious proof of man's total depravity. 'Ye must be born again.' 'Except a man, [except any one] be born again, he cannot see the kingdom of heaven.' Why is such a change universally necessary, if men in their natural state have any degree of holiness? The Bible promises heaven to those who have holiness, or love to Christ, in any degree. Even one who gives a cup of cold water to Christ's disciples from a right motive has the promise of a future reward. The existence of holiness in man is in Scripture attributed to the renewing- of the Holy Ghost. In all its branches and in all its degrees, it is the fruit of the Spirit. It is perfectly obvious then that man, in his natural, unrenewed state, is wholly destitute of holiness, and that his moral affections are all sinful.
In support of our doctrine I might urge the failure of the most powerful motives to induce unrenewed man to turn from sin and believe in Christ. When the persuasive considerations of the Gospel are clearly presented before the mind of a sinner, they would certainly influence him to the exercise of penitence, faith, and love, if he had any degree of moral rectitude. What could be a more decisive proof that his moral nature is entirely perverted, than the fact that the amiable and glorious character of Christ is held up before him, and yet excites no love; that when the condescending kindness and grace of God are described to him, he feels no gratitude; and that he renders no cordial obedience to that law which is holy, just, and good? What greater evidence of man's total moral corruption could there be than this, that he is not persuaded to forsake sin and follow Christ, either by the threat of eternal misery, or the offer of eternal blessedness?
I appeal for proof, finally, to the experience and consciousness of the enlightened Christian. When he reflects upon the exercises of his own heart, and compares them with the demands of God's perfect law, he is satisfied that in him, naturally, there was no good thing, that he was wholly alienated from God, and that the first existence of holy affection in his heart was the fruit of regenerating grace. And he is equally satisfied that he is still dependent, and must continue to be dependent for all holy affections, upon the sanctifying influence of God's Spirit; and that, if that Holy Spirit should be wholly taken from him, he would sink at once into a state of entire moral pollution. If any Christian affirms that he had any holy affections, or performed any holy actions, in his natural state, it must be because he uses words in a very vague sense, or because he has not properly reflected on the nature of that divine law which is the standard of holiness".
From An Essay on Native Depravity by Leonard Woods, D. D., published in 1835; William Pierce Co., Boston