The common mode of reasoning adopted by the religion of the day is this: some sins are compatible with true faith, viz. sins of infirmity; therefore, wilful transgression, or what the text calls "departing" from God, is compatible with it also. Men do not, and say they cannot, draw the line; and thus, from putting up with small sins, they go on to a sufferance of greater sins. Well, I would take the reverse way, and begin at the other end. I would force upon men's notice that there are sins which do forfeit grace; and then if, as is objected, that we cannot draw the line between one kind of sin and another, this very circumstance will make us shrink not only from transgressions, but also from infirmities. From hatred and abhorrence of large sins, we shall, please God, go on to hate and abhor the small.
--Blessed John Henry Newman, “Transgressions and Infirmities”, Parochial and Plain Sermons, Vol. 5