If I ask him, will God forgive me these things, for which I am so sorry and whose memory brings me such pain? things into which I slip and fall, even though I am disgusted by them, for which my feelings of guilt and the pain which they produce in me are sharper than a scorpion's sting? Even though I hate them, I remain in them, and though I repent of them with travail, like a wretch I return to them (Isaac the Syrian, Ascetical Homilies II/40, 15).
In the course of a long discussion on justification by faith through God's grace, brother Isaac gives us the following sage advice, appropriate for all of us who may feel bogged down by our sin:
For if someone's happiness depends on his own behavior, it will be a deceptive one. More than that: it will be an impoverished happiness! And not only will his happiness be impoverished, but also his understanding. For whoever is made happy because he has understood that God is indeed good, this one is comforted with a lasting comfort and he is happy with true happiness; and this because, as I've said, his soul has been made wise and has understood that truly the goodness of God is boundless (III/6, 22).
It is all too easy, in the course of our struggles and fights against the flesh, to become overwhelmed by the sense of our own sinfulness. Seeing our weaknesses, seeing how we are constantly tempted, seeing how prone we are to fall and to fail to keep that which God requires of us, we may too easily trapped in despair and a kind of spiritual lifelessness. It paralyzes us and keeps us from praying, from worshiping, from seeking fellowship with God.
When this happens to us, we have allowed our own behavior to be the condition of our happiness: if we do what is good, we feel good and are happy; if we do what is bad -- which happens more often than the former -- we are disappointed and our happiness and joy disappear. Worse than that, this joylessness and despair make it even more difficult to get back on the horse, so to speak, and to do what is good. It is a downward cycle, a vicious circle.
Isaac's advice for us is to ground our happiness in the knowledge and understanding that God is good, immutably and eternally good! That is the only way our happiness will be lasting, and thus we will have the strength to do what we ought, knowing that God is good and he accepts.
And this goodness, for Isaac, is grounded in the fact of salvation that God has provided for us. Especially important is justification by faith: even the slightest faith, the slightest turning toward God, is counted as righteousness, and all our sin is done away with, so we can start with a blank slate. Whoever doesn't have deeds, but merely believes in the One who justifies sinners, that one sees the faith of his conscience reckoned by God as righteousness (III/6, 12). God is eager and waiting to justify sinners: Therefore, even if a person be sinful, taking advantage of even the smallest pretext, God declares him righteous right away; and for the good deed of a single day He forgives the wickedness of his entire life (III/6, 34).
In his evangelistic zeal, and so impressed by God's mercy, Isaac even uses language of trickery and schemes: In any case, although [God] gives power to the will so that it might not fall into sin, and though he is the fount of every good, yet He is delighted to declare us righteous. As I was saying, He wanted this so that, making use of every available device, he would be able to enjoy all persons as righteous, and so as to contain every man in the number of these righteous persons (III/6, 36).
God was wise, and so in his goodness he provided for us a way out of trouble: Because in his fully merciful understanding God knew that hardly one man in ten thousand could have entered the Kingdom of heaven if complete righteousness were asked of them, therefore he gave everyone a treatment fitting for all: repentance. In all their days and at any moment they have an opportunity to set themselves right easily through this treatment: through the compunction of their hearts they can wash themselves at any moment of the stains which they might suffer, renewing themselves every day through repentance (II/40, 8). How good is God to provide for us! Elsewhere he writes that God asks of us merely the smallest volition, and His grace gives abundantly and He forgives our sins (III/6, 17).
We ought to think about God's goodness all the time, because this will transform us and give us true happiness. It will give us strength. Let us strive in the meditation of these things, because the discernment that comes from it is great, and the happiness it brings is measureless. This is the delight of angels! (6, 44) Indeed it is a way of having fellowship with God: Remaining at these things, the intellect speaks with God at every moment (6, 51).