Not merely a knowledge of history...

But the faith that justifies is not merely a knowledge of history.  It is to believe in God's promise.  In this promise, for Christ's sake, forgiveness of sins and justification are freely offered.  And so that no one may suppose that this is mere knowledge, we will add further: it is to want and to receive the offered promise of forgiveness of sins and of justification.
~BOC, AP, AP, IV (II), 48