Luther on Christian Truth

Martin Luther's response in Bondage of the Will to Erasmus describing himself as one who was "far from delighting in assertions":

For not to delight in assertions, is not the character of the Christian mind: nay, he must delight in assertions, or he is not a Christian.

To clarify his use of the term "assertions," Luther goes on to write:

But, (that we may not be mistaken in terms) by assertion, I mean a constant adhering, affirming, confessing, defending, and invincibly persevering. Nor do I believe the term signifies any thing else, either among the Latins, or as it is used by us at this day. And moreover, I speak concerning the asserting of those things, which are delivered to us from above in the Holy Scriptures.