David Powlison on living the Christian life in your own power, compared to living in His mercy:
Since Christ is both Giver and Gift, attempts to change without grace are barren of the very purpose, power, and Person that change is about. Self-manufactured changes do not dislodge almighty me from the center of my tiny self-manufactured universe. Still in the futility of my mind and the hardness of my heart, I act a bit different and feel a bit different. Successful living without grace describes mere self-reformation: get your act together, save your marriage, get off your duff and get a job, pull yourself together, get a grip. Failure in living describes failed self-efforts: when you can’t get a grip, when life spirals out of control or down the drain, you despair. Christ-less, grace-less attempts at change conclude either with the praise of your own glory or with your shame.
But in mercy, God purposes to give us Himself. Ephesians 1 marvels at the glory of the grace that gives us glory in Christ. Ephesians 2 marvels at the sheer goodness of God and God’s grace, what a friend of mine calls “God’s thermonuclear goodness.” His goodness is of an all-consuming intensity, like the nuclear furnace of the sun. In His presence, we, the dead in sin, children of just wrath, would be incinerated by goodness. But Christ’s incalculable grace multiplies goodness times forgiveness times kindness times mercy. Christ carries us into the center of the fiery sun of the living God. Ephesians 3 marvels that the light has called all nations into grace, and pleads with God that we would understand such a love as this.