The Pelagianizing Romanist says, Lust, or concupiscence, brings forth sin, therefore it cannot be sin, because the mother cannot be the child. We reply, Concupiscence brings forth sin, therefore it must be sin, because child and mother must have the same nature. The grand sophism of Pelagianism is the assumption that sin is confined to acts, that guilty acts can be the product of innocent condition, that the effect can be sinful, yet the cause free from sin--that the unclean can be brought forth from the clean.
Charles Porterfield Krauth, Conservative Reformation & Its Theology
concupiscence, sin