Cardinal Manning explains: “There are many definitions of [sin], and one is this: it is the transgression of the law. ‘Sin is the transgression of the law’ (1 Jn 3:4). God is a law to Himself; His perfections are the law of His own nature; and God wrote upon the conscience of man, even in the state of nature, the outline of His own perfections. He made man to know right from wrong; He made him to understand the nature of purity, justice, truth, and mercy. These are perfections of God, and on the conscience of man the obligations of this law are written. Every man, born into the world in a state of nature, has this outline of God’s law written upon him, and sin is the transgression of that law.”
“Another definition of sin is: any thought, word, or deed contrary to the will of God. Now, the will of God is the perfection of God Himself—holy, just, pure, merciful, true; and anything contrary to these perfections in thought, word, or deed is sin. The conformity of man to the will of God, to the perfections of God, is the sanctity or the perfection of the human soul; and the more he is conformed to the will of God, the holier and more perfect he is.”
“The malice, then, of sin consists in this, that it is a created will in conscious variance with the uncreated will of God. God made us to His own image and to His own likeness; He gave us all that He could bestow upon us. He could not bestow upon us His own nature, because that is uncreated, and no creature can partake of the uncreated nature of God; but God could bestow, and He did by His omnipotence with His mercy, bestow upon us His likeness, His image, an intelligence and a will, a heart and a conscience, so that we become intelligent and moral beings. The malice of sin consists, then, in this: that an intelligent creature, having a power of will, deliberately and consciously opposes the will of its Maker. The malice of sin is essentially internal to the soul. The external action whereby the sinner perpetrates his sin adds indeed an accidental malice and an accidental increase of wickedness.”
Quotations from Henry Edward Manning, Sin and Its Consequences, 2d ed. (London: Burns and Oates, 1874).