"Finally, for all the positive things we can say about the new birth it is right to remind ourselves that, as Boston notes, it is an imperfect change. Just as a newborn baby is not a mature man, so a newborn Christian has plenty of developing to do. It is important that we do not expect too much. Thomas Watson says, ‘The new creature is but begun here; it is not perfected or drawn in all its orient colours till it comes to heaven.’ Calvin warns, ‘There still remains in a regenerate man a fountain of evil, continually producing irregular desires.’ The fight against sin goes on to the end. We should pray with Wesley, 'Finish, then, Thy new creation; Pure and spotless may we be.' It is not ‘Till in heaven we take our place’ that we will know the perfect restoration found in Christ."
From my book What the Bible teaches about being born again, p 43