In preserving that, He also preserves their faith and their obedience, so that, though imperfectly, they do continue to believe and to keep God's commandments. Nor may the believer want them to be preserved and try to preserve them. We do well to remember that according to this doctrine, it is saints, that is, those who are holy , who are preserved, and they are preserved unto more holiness. That they are not holy by their own strength makes no difference. Nor are they preserved apart from faith.
Faith is always the way of, though never the reason for, salvation.
They are not preserved from temptation, from weakness, or from falling into temptation and sin. How important it is to remember that. They are not preserved from falling, but from falling away. Due entirely to their own weakness and sinfulness, believers can and do fall into temptation and sin. That believers can and do fall is demonstrated in Scripture by the examples of men like David and Peter.