Philippians 1:6 assures us that, “He who began a good work in us will be completed until the day of Christ Jesus”.
When Paul says that he is “confident” of these things, he uses a very strong Greek word that really means “fully persuaded” or “absolutely certain.” It means to have no doubt whatsoever about the outcome. This makes sense when you understand that salvation is God’s work from start to finish. If it had to do with us as humans it might get left undone – not so with God. He finishes what he starts. When God determines to save a person, He saves!
Romans 8:37-39 (NIV) No, in all these things we are more than conquerors through him who loved us. For I am convinced that neither death nor life, neither angels nor demons, neither the present nor the future, nor any powers, 39neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord. This is an exhaustive list and is intended to leave no room for misunderstanding. Nothing can separate us from God.