Ligonier offers a brief but important teaching on the permanence of regeneration.
[I]f it were up to us, none of us would be able to die in a state of grace. This does not mean that sanctification is passive or that we should sit back and let God do all of the work. Paul tells us in Philippians to work out our salvation in fear and trembling (2:12). Nevertheless, God undergirds all of our efforts to pursue maturity in Christ. His sovereign presence and saving power is what ultimately keeps us in the faith (v. 13).