St. Anthimus the Georgian: The true fast is that from sin

 What profit is it for the body to be empty of food, but the soul full of sins? What profit is it to be pale and withered from fasting, but burning with envy and covetousness? What profit is it to abstain from wine, but to be drunk with the venom of anger? What profit is it to not eat meat, but to rend the flesh of our brethren by slander? What profit is it for us to cease from things which are sometimes allowed, but to do things that are never allowed? God loves and honors those who keep themselves from what is forbidden.
+St. Anthimus the Georgian, from Romanian Patericon 147, Works and Teachings #29.

St. Anthimus the Georgian: Motivation for sin

Man sins in three ways: form weakness, from ignorance, and from an evil will. Sin committed from weakness is against God the Father, since the Father is called Almighty. Sin committed from ignorance is against the Son, since the Son of God is called Wisdom. Sin committed from an evil will is against the Holy Spirit, for the Holy Spirit is called Good.

The Lord will more easily forgive a man who sins from weakness or from ignorance, if he will repent. For David says, "The sins of my youth and my ignorance, O Lord, remember not" (. But whoever sins from an evil will against the Holy Spirit will not easily be forgiven by God. For the Lord says:

+St. Anthimus the Georgian, Works and Teachings, #49-50, in Romanian Patericon Volume 1, by Archimandrite Ioanichie B