Sunday I preached on "Sinners and Saints," leading our people to see that as followers of Christ we are both, simultaneously. Understanding this reality promotes much needed humility and hope. I've already recommended one relevant book, but it's kind of a biggie. Let me recommend another, much smaller book that has a tremendous influence in my life. John Calvin's Golden Booklet of the True Christian Life is a must have. Check out some of Calvin's words on spiritual growth, aims and expectations.
We should not insist on absolute perfection of the gospel in our fellow Christians, however much we may strive for it ourselves.
It would be unfair to demand evangelical perfection before we acknowledge anyone as a Christian. There would be no church if we set a standard of absolute perfection, for the best of us are still far from the ideal, and we would have to reject many who have made only small progress.
... No one in this earthly prison of the body has sufficient strength of his own to press forward with a sure degree of watchfulness, and the great majority [of Christians] are kept down with such great weakness that they stagger and halt, and even creep on the ground, and so make very slight advances.
But let everyone proceed according to his given ability and continue the journey he has begun. ...Let us not cease to do the utmost, that we may incessantly go forward in the way of the Lord; and let us not despair because of the smallness of our accomplishment.
This book finds its way into my hands at least a couple time a year. If you don't have it, get it.