Do you mortify; do you make it your daily work; be always at it whilst you live; cease not a day from this work; be killing sin or it will be killing you.Of the Mortification of Sin in Believers Chapter 2
That is why the unregenerate person cannot understand the urgency of the gospel message: until they see the depth of their sin and the holiness of God, they find no reason to seek remedy for their condition.
When I turn to the map of the world I must say the same thing. It matters not what quarter I examine: I find men's hearts are everywhere the same, and everywhere wicked. Sin is the family disease of all the children of Adam.Old Paths, Ch 7
At the heart of all sin is a lie. The lie says to all of us in our sin, "The act you are now doing, the desire or attitude you are now feeling is not very bad because there are much worse things, not very bad because everyone else experiences the same things, not very bad because you can't help it, not very bad because there is no God, or, if that won't work, God knows you are but frail and weak and he will tolerate and pity your sin." There are a thousand distortions of the truth which sin brings with it into the human heart, so that Jeremiah cries out, "The heart is deceitful above all things and desperately corrupt; who can understand it?" (17:9).
You can never part with sin soon enough; it is a cursed inmate, that will surely bring mischief upon the soul that harbours it. It will set its own dwelling on fire.Works 7:147
In answering this question I have tried hard to maintain the free choice of the human will. But the grace of God prevailed. Augustine: earlier writings, Volume 1953, Part 2 (Page 370)
But, during all those years, where was my free will? What was the hidden, secret place from which it was summoned in a moment, so that I might bend my neck to your easy yoke and take your light burden on my shoulders, Christ Jesus, my Helper and my Redeemer? How sweet all at once it was for me to be rid of those fruitless joys which I had once feared to lose and was now glad to reject! You drove them from me, you who are the true, the sovereign joy. You drove them from me and took their place, you who are sweeter than all pleasure, though not to flesh and blood, you who outshine all light yet are hidden deeper than any secret in our hearts, you who surpass all honour though not in the eyes of men who see all honour in themselves. At last my mind was free from the gnawing anxieties of ambition and gain, from wallowing in filth and scratching the itching sore of lust. I began to talk to you freely, O Lord my God, my Light, my Wealth, and my Salvation. Confessions Book IX Chapter I
The fallen condition of all humankind in Adam is not the result of mere social conditioning but is such "by nature" (φύσει, physei)Ephesians, Evangelical Exegetical Commentary (Bellingham, WA: Lexham Press, 2015), 152.
yet they preach that our visible sun spreads its rays over all manner of offal, but keeps them clean and pure. Therefore, if pure things which are visible can be touched by visible things which are unclean and not share their pollution how much more did the unchangeable and invisible Truth, receiving a soul through the spirit and a body through the soul, take on the whole man without contamination to itself and free him from all infirmities?De agone christiano, c18 n20
some things are sins and punishment of sin simultaneously, some are sins and the cause of sin, but others are sins and the cause and punishment of sin.The Sentences, Book 2, Distinction 36, C1