Who does not know how difficult it is, without God’s special grace, for a sinner to turn from the way of sin that is so dear to him to the path of virtue?
How deeply sin takes root in the heart of the sinner, and in all his being — how it gives the sinner its own way of looking at things, by means of which he sees them quite differently to what they are in reality, and shows him everything in a kind of alluring light.
It is for this reason that we see that sinners very often do not even think of their conversion, and do not consider themselves to be great sinners, because their eyes are blinded by self-love and pride. And if they do consider themselves sinners, then they give themselves up to the most terrible despair, which overwhelms their mind with thick darkness and greatly hardens their heart.
-St John of Kronstadt