Augustine has been deemed rather… problematic at different points in the history of the Church and Christianity as a whole.
We all bring our baggage before the Lord - who promptly turns us upside down.
If you read through Augustine’s Confessions, he had the equivalent of the modern University experience when he moved to Carthage - replete with a variety of amorous affairs.
To be as blunt as possible - he loved sex. Now that might seem a bit intuitive for a human being

, but as he goes on to say in his Confessions and other writings - he loved it to the point of blocking out his connection to the divine. So this shouldn’t be interpreted as him having a normal healthy relationship - he was by his own words a slave to it… what modern psychology might classify as sexual addiction.
How he cured himself of it? Cold Turkey more or less - although the manner by which he did it (kicking out his concubine) would be heavily frowned upon by modern morality (heck even by ancient morality). He basically had to isolate himself from the temptation.
Even in his old age, he complained about still feeling the tug and urge for it.
His struggles play into his ideas about Original Sin.
Extrapolating from his own struggles, Augustine believed that Humanity before the Fall had complete control of his or her body. This is especially true over man and womans generative organs - Augustine believed that the disobedience of the body to the higher human faculties of the Mind and the Will was a punishment of the Fall.
If you dig through his
City of God, he speculates that the reason why Adam/Eve fell in the first place was because of a flaw our creation. In this he’s actually elaborating on a position held by Athanasius.
God made us from Nothing. When we turn away from God, who is pure Being, we are in fact turning back toward Nothing-ness. So when via Pride we flout the Divine will and start living for ourselves against God’s will - living for oneself “is not as yet to be nothing, but to approximate nothing.”
As some of the other commentators on this thread mention, the Fall, at least in Augustine’s view, tainted human existence by enfeebling/destroying free will. Adam’s sin radically transformed Human Nature itself.
So that leaves human beings in a state of well…bad. Its only by Divine Grace, can humans have any ability to fix their situation.
The Other Church Fathers tend to look at this narrative with some skepticism.
Our Orthodox Brethren point out to the fact that many of the Church Fathers, interpret Adam’s sin as having consequences for humanity - but people do not bear the Guilt for it, that’s Adam and Eves to bear alone.
Essentially, they deny Augustine’s idea that mankind lives in a state of total depravity post-Fall. We are tarnished yes, but the situation isn’t as pessimistic as Augustine makes it out to be.
There’s also an element of wondering if Augustine is extrapolating too much from his own personal experiences to fit the condition afflicting all of mankind.