I'd encourage anyone to look at Martin Luther's 1518 Heidelberg Disputation. A lot is often said about Luther's 95 Theses against Indulgences, but if you really want to see some of central kernels of Evangelical theology, the Heidelberg Disputation is really the place to start looking.
Luther argues, several theses in, that "Although the works of man always seem attractive and good, they are nevertheless likely to be mortal sins."
I have nothing to offer before God as good. All my righteousness is really unrighteousness. Every good work I do thinking and believing I am justified by the Law is, in fact, a sin and compounds my guilt before the Law which declares me in every way guilty. I am a sinner. Even in my good works, even in my best works, in every good I think I do, in every righteous deed I consider righteous, I am a sinner. God, have mercy on me.
Just how deep does this abyss of despair that lay within us go? All the way to deepest and darkest hell.
So, therefore, knowing just how depraved we are, hear this amazing word of grace: God loves you and Christ died for you. How deep, how unplumbable are the fathomless depths of God's love for us. That while still sinners Christ died for us.
-CryptoLutheran