I think I count three questions, each with an answer attached. If my understanding of Scripture is correct, your answers are misguided, and your interpretation of the verses you cite confused. Salvation is granted immediately upon acceptance of (that is, belief in) Christ as Savior. See John 3:16, 36, and other texts that stress that salvation is a present possession. We believers have (not may get) salvation. True, it will be fully realized when we get to heaven, but until we get there—by death or by the Second Coming—we are saved and, therefore, eternally safe. The gift of salvation is not given on the basis of sacrificial living for God, and it is not withdrawn for failure to live sacrificially. It is guaranteed by an unchanging, irrevocable promise of God (see John 10:27–30).
Those who “decide to come out of (God’s grace)” were never “under it.” They are apostates, not backsliders or lukewarm believers. Ponder the texts cited here, and rejoice in “the kindness and love of God our Savior . . . [who] saved us, not because of righteous things we had done, but because of his mercy” (Titus 3:4–8).