Roland Bainton on Luther's views:
"The Christian is bound every day to fail, yet he is not sunk. He is at once a sinner and yet saved. If he makes no pretense to goodness but in humility and gratitude endeavors to conform himself to the divine purpose, e will be able to carry on despite every shortcoming."
Taken from pg. 53 of " The Reformation of the Sixteenth Century" Beacon Press, 1952.