"Beware also, daughters, of certain kinds of humility which the devil inculcates in us and which makes us very uneasy about the gravity of our past sins. There are many ways in which he is accustomed to depress us so that in time we withdraw from Communion and give up our private prayer, because the devil suggests to us that we are not worthy to engage in it. When we come to the Most Holy Sacrament, we spend the time during which we ought to be receiving grace in wondering whether we are properly prepared or no. The thing gets to such a pass that the soul can be made to believe that, through being what it is, it has been forsaken by God, and thus it almost doubts His mercy. …]
Pay great attention, daughters, to this point which I shall now make, because sometimes thinking yourselves so wicked may be humility and virtue and at other times a very great temptation. Humility, however deep it be, neither disquiets nor troubles nor disturbs the soul; it is accompanied by peace, joy, and tranquility. Although, on realizing how wicked we are, we can see that we deserve to be in hell, and are distressed by our sinfulness, and rightly think that everyone should hate us, yet, if our humility is true, this distress is accompanied by an interior peace and joy of which we should not like to be deprived. Far from disturbing or depressing the soul, it enlarges it and makes it fit to serve God better. The other kind of distress only disturbs and upsets the mind and troubles the soul, so grievous it is. I think the devil is anxious for us to believe that we are humble, and, if he can, to lead us to distrust God.
When you find yourselves in this state, cease thinking, as far as you can, of your own wretchedness, and think of the mercy of God, and of His love and His sufferings for you. If your state of mind is the result of temptation, you will be unable to do even this, for it will not allow you to quiet your thoughts …] it will be a great thing if you can recognize it as a temptation."
-St Teresa of Avila, “The Way of Perfection”