Moderns tend to regard sin in a quantitative manner - as if the question of whether someone is 'a sinner' could be decided by weighing his good against his bad qualities and seeing where the preponderance lay; or taking an average of his behaviour and seeing whether it was on the side of sin or not.
This metaphor is wrong because the calculus is atheist - the quantitative calculus assumes the non-existence of God; indeed it is an attempt to retain morality after God has been subtracted from the worldview.
Sin is not about good and bad acts but about being turned towards or away-from God.
A man who does not sin is not a man that does only good acts, he is a man turned always towards God.
A sinner is a man who turns away from God, sometimes. In other words everyone.
Yet it may take just one single sin to keep a man turned-away from God, permanently.
It could be something 'trivial' - some clinging to something worldly, some mere distraction. But if it keeps a man turned away from God it will suffice: it does suffice.
In the end damnation is refusal of the offer of salvation. The offer is made to all, perhaps. Anything which leads a man to refuse salvation when offered is a deadly sin, deadly to his soul.
The more trivial-seeming, the more effective the sin may be - since it arouses no revulsion, no reaction; we do not guard against it....
And we may feel that we can compensate for trivial-seeming sins, by heroic good works (or something) on the quantitative concept. But so long as we stay turned-away from God nothing will work.
This is the particular hazard of modernity. It is asif the whole of modern life is set up to keep us turned away from God all the time yet by such trivial worldly matters that we feel that - surely - we cannot be sinners, surely the balance must be in our favour - surely we we not be damned for merely wasting our lives in frenetic busyness?
No we won't be damned, we will refuse salvation - indeed, we may not even recognise or understand the offer.
A consequence is that Christianity ought to be - in these modern conditions - a turning-towards God; I mean the main goal should be to help people to glimpse God (and know that this is God they glimpse) and thereby reveal their habitual state of being turned away. Moderns cannot be terrified out of their sin, because they see no place to escape from the world - they need to be shown a glimpse of the exit.