The ultimate sin is to despair of God's mercy. That is to limit it, to make our ego its limit, whereas it is boundless.
OLIVIER CLÉMENT The Roots of Christian Mysticism
The Mercy of God has no limits, nothing is too great for it. That is the reason why anyone who despairs of it is the author of his own death.
JOHN CLIMACUS The Ladder of Divine Ascent, 5th Step