Luther's call to follow the "stubbornness" of the apostle Paul

Here is a quote from Luther on the model of  inspired tenacity given by the apostle Paul which I used in last Sunday's sermon on Galatians 2:1-10:

Let us learn this kind of stubbornness from the apostle. We will suffer our goods to be taken away, our name, our life, and all that we have, but the gospel, our faith, Jesus Christ, we will never suffer to be wrested from us:  and cursed be that humility that here abaseth and submitteth itself; nay, rather let every Christian be proud and spare not, except he will deny Christ.  Wherefore, God assisting me, my forehead shall be harder than all men’s foreheads. Here I take my motto, “Credo nulli.”  I will give place to none.  I am, and ever will be, stout and stern, and will not give one inch to any creature.  Charity giveth place, “for it suffereth all things, believeth all things, endureth all things:” but faith giveth no place (as cited in John Brown, Galatians, p. 76).