Grace is eternal (2 Tim. 1:9), immutable (Rom. 11:29), sovereign (Rom. 9:11-24), effectual (Eph. 2:8-9; John 6:37, 39, 44, 63-65), and destroys all room for human boasting (1 Cor. 1:29-31; 4:7). It means that the Triune God gets all the praise, honor, and glory for our salvation: The Father for planning it, the Son for purchasing it, and the Holy Spirit for applying and uniting us to it (Eph. 1:2-14).
Christ is not only efficient, but is alone sufficient for salvation (Hebrews 9:12; 10:10) such that our own merit or works righteousness can do nothing to either attain or maintain our justification. The assistance of grace does not even depend on the humility or obedience of man ... for it is a gift of grace itself that we are obedient and humble ...as the Apostle says, "What have you that you did not receive?" (1 Cor. 4:7), and, "But by the grace of God I am what I am" (1 Cor. 15:10). Faith is, therefore, not a product of our un-regenerated human nature (John 1:13, 6:63-65; Rom 9:16) but is exercised as the infallible result of the work of the Holy Spirit opening our eyes and ears to the beauty of the gospel, turning our heart of stone to a heart of flesh and uniting us to Christ. - Monergism.com