What is faith?

“The faith of human beings is their heartfelt Yes to Jesus Christ and to the divine judgement that has been passed and enacted. This Yes comes from the heart, because the divine judgement has come into the heart of believers, striking them in the centre of their existence.... The affirmation, the Yes that the believer says to God’s judgement, is not just some arbitrary word which could just as well be replaced by some other word. Rather, by this Yes ... the whole person, human existence as a whole, is expressing itself. The Yes of faith is the most concentrated expression of human existence. When we believe, our whole existence becomes a single Yes by which we are affirming God’s decisive judgement over all human existence and thus over our own existence.” —Eberhard Jüngel, Justification: The Heart of the Christian Faith(Edinburgh: T&T Clark, 2001), p. 238.