According to Scripture, man should be in complete conformity with the divine will (conformitas cum voluntate Dei), as this is revealed in the divine Law (νόμος). Every departure from the norm of the divine Law is sin (ἀνομία), no matter whether it consists in a state or condition (status, habitus) or in actual deeds (actiones internae et externae). Considered etymologically, sin is, in the first place, a negative concept (ἀνομία), and as such it denotes man's lack of conformity with the divine Law (carentia conformitatis cum lege). So Scripture defines sin (1 John 3, 4: "Sin is lawlessness," ἀνομία). But sin is also a positive concept, and as such it denotes opposition to, or transgression of, the Law, so that positively sin is a violation of the Law. So, too, Scripture defines sin (1 John 3, 4: "He does lawlessness, τὴν ἀνομίαν ποιεῖ; Matt. 7, 23: "Ye that work lawlessness," ἐργαζόμενοι τὴν ἀνομίαν). The reason for this is obvious. Man, destitute of righteousness, is at the same time in constant, active rebellion against the divine Law. In other words, after the Fall man wilfully refuses to recognize the obligation he has toward God (Rom. 1, 18. 32) and constantly breaks the divine Law, since his carnal mind is enmity against God, Rom. 8, 7. On the basis of Holy Scripture we therefore describe sin, a) negatively, as a lack of righteousness or of conformity with the divine will (carentia conformitatis cum lege); b) positively, as actual opposition to the divine will (carnalis concupiscentia sive inclinatio ad malum).
When defining sin, we must beware of the error of the papists and rationalists, who condemn as sinful only those evil acts which are done consciously and deliberately. Against this pernicious error the Apology testifies: "But in the schools they (the papists) transferred hither from philosophy notions entirely different, that because of passions we are neither good nor evil, we are neither deserving of praise nor blame. Likewise, that nothing is sin unless it be voluntary (inner desires and thoughts are not sins if I do not altogether consent thereto). These notions were expressed among philosophers with respect to civil righteousness and not with respect to God's judgment." Art. II (I), § 43. According to Scripture both the evil deeds, 2 Sam. 12, 13, and the evil thoughts and desires, Jas. 1, 15; Rom. 7, 17; Matt. 5, 28, are sins, even if they are done unknowingly and without deliberation, Rom. 7, 19; 1 Tim. 1, 13. Indeed, according to Scripture even the inherited corruption, which yet cleaves to the Christian and which he earnestly deplores, is sin in an absolute sense, Eph. 2, 3; John 3, 5. 6; Rom. 7, 19. 24.