[God] also made us sufficient as ministers of the new covenant, not of the letter but of the Spirit…But their minds were hardened. For until this day the same veil remains unlifted in the reading of the Old Testament [old covenant], because the veil is taken away in Christ.
(2 Corinthians 3:6, 14)
We have seen that godly characteristics develop in our lives through the working of God's grace within us. We now begin consideration of a closely related subject: a contrast between living by the old covenant or by the new (by law or by grace). The ongoing choices we make here determine whether we will be living by man's sufficiency or by God's. Various contrasting terms describing these significant choices are set forth in the third chapter of 2 Corinthians. Verses 6 and 14 set the basic context, the differences between the new covenant and the old: "[God] also made us sufficient as ministers of the new covenant…For until this day the same veil remains unlifted in the reading of the Old Testament [old covenant]."
One of the drastic differences between living by the old covenant or the new is seen in verse 3: "You are manifestly an epistle of Christ…written not with ink but by the Spirit of the living God" (2 Corinthians 3:3). People write letters on paper, using ink to record the message. God writes His message in people's lives, using His Spirit as the instrument. What a vivid contrast, "ink" versus "the Spirit of the living God." Ink is a natural resource. It is available to all humankind, regardless of their relationship with God. Ink is not a life-giving or life-developing entity. It is a mere element of the kingdom of man. When we choose to live by the old covenant (the law), the only resources we have to draw upon are natural human resources. We are writing our own letter of life, and we have selected man's sufficiency, not God's. Such resources are as spiritually powerless as ink.
On the other hand, those who live by the new covenant of grace have the Holy Spirit supplying the mighty, heavenly, sufficiency of God. Think of the radical difference, ink versus the Holy Spirit. God wants us relying on His Spirit. He wants us living by His sufficiency, not ours.