Let us thank God, therefore, that we have been delivered from this monster of uncertainly and that now we can believe for a certainty that the Holy Spirit is crying and issuing that sigh too deep for words in our hearts. And this is our foundation: The Gospel commands us to look, not at our own good deeds or perfection, but at God as He promises, and at Christ Himself the Mediator. (God) says" "I am giving my own Son into death, so that by His blood He might redeem you from sin and death."
Here I cannot have any doubts unless I want to deny God altogether. And this is why our theology is certain: It snatches us away from ourselves...so that we do not depend on our own strength, conscience, experience, person or works but depend...on the promise and truth of God, which cannot deceive.
Martin Luther
Luther's Works, Volume 26
