"There is hardly a page of Scripture on which it is not clearly written that God resists the proud and gives grace to the humble"
Augustine, Reply to Faustus
Unless we understand the freeness and sheer magnitude of the grace of God in the gospel, and the workings of grace in the life of the believer by the ministry of the Holy Spirit, we will be left with either a warped view of our own works or a distorted view of God's gracious work. In all likelihood, it will be both.
Grace restores our sanity and our sight.
We see our sin, in greater measure, from God's perspective.
We see his grace, the gift and the Giver, in true perspective too.
Unless we have this vision we will descend into the insanity of trusting in works righteousness, either from believing that our best works merit the favour of God, or in despair because in unbelief we lament our lack of them, as if the free gift of God were not what it is, the giving of eternal life through Jesus Christ our Lord.
At root, to despair because of sin is still to be looking within for the cause of God's acceptance of us.
To look away from ourselves, to the Father's love in Christ, to the Son's death in our place and to his resurrection from the grace, to his finished work on our behalf, is to see things as they really are.
Woe even to those of praiseworthy life if you put their life under scrutiny and remove mercy.
If anyone lists his true merits to you, what is he enumerating before you but your gifts?Augustine, Confessions, Book IX:xiii (34)