"Let men therefore acknowledge, that inasmuch as they are born of Adam, they are depraved creatures, and therefore can conceive only sinful thoughts, until they become the new workmanship of Christ, and are formed by his Spirit to a new life... Nor is it any proof to the contrary, that carnal and profane men often excel in generosity of disposition, undertake designs apparently honourable, and put forth certain evidences of virtue. For since their mind is corrupted with contempt of God, with pride, with self-love, ambition, hypocrisy, and fraud; it cannot be but that all their thoughts are contaminated with the same vices... We must, therefore, acquiesce in the judgment of God, which pronounces man to be so enslaved by sin that he can bring forth nothing sound and sincere. Yet, at the same time, we must remember, that no blame is to be cast upon God for that which has its origin in the defection of the first man, whereby the order of the creation was subverted. And further, it must be noted, that men are not exempted from guilt and condemnation, by the pretext of this bondage: because, although all rush to evil, yet they are not impelled by any extrinsic force, but by the direct inclination of their own hearts; and, lastly, they sin not otherwise than voluntarily."
John Calvin, Commentary on Genesis 8:21.
"Then the Lord said in His heart, 'I will never again curse the ground for man's sake, although the imagination of man's heart is evil from his youth...'"