Cardinal Manning states that the second effect of a sin of omission is that it produces in a person “a kind of sluggishness in everything that he does. Outwardly, perhaps, the actions of his life are to the eye of his neighbours just the same as they were before; but to the eye of God, a change has passed upon him.”
“He begins to do his duties with a certain carelessness, so that the motives from which he acts, and the manner in which he does even things that are good, are not what they were. . . . He begins to be unpunctual. He puts off his prayers in the morning; he forgets them till noonday, and perhaps at noonday he says only half of them.”
“Then comes irregularity. That is to say, he used to live by rule, he used to take the will of God as his will, and try to conform himself to it as well as he could; but now he lives by the rules of the world, the customs of men, and I may say, at haphazard and at random.”
“The next step is this: he begins openly to leave duties undone.” He ceases to act according to the light and direction of the gifts of the Holy Spirit. “These seven gifts have been described as the sails of a ship; the more we spread them the more we speed the soul; and the more we speed the soul the more we are carried onwards in the way of salvation.” The graces of faith, hope, and charity soon lose their power in the person who has ceased to pray.
“Next comes neglect of the manifold duties of charity towards our neighbour. . . . Our Lord says that at the Last Day He will say: ‘I was hungry, and ye gave Me no meat; I was thirsty, and ye gave Me no drink; I was naked, and ye clothed Me not’ (Mt 25:35-36).”
“Lastly comes the sin of omission of love towards God. We are bound to love God with our whole heart and our whole mind; and the man who commits sins of omission in charity towards his neighbour fails also in charity towards God, for ‘he that loveth not his brother whom he seeth, how can he love God whom he seeth not?’ (1 Jn 4:20) . . . The sin of omission at last threatens the life of the soul: for the life of the soul is charity.”
Quotations from Henry Edward Manning, Sin and Its Consequences, 2d ed. (London: Burns and Oates, 1874).