1. Letter to Melanchthon, August 1,1521 (American Edition, Luther's Works, vol. 48,pp.281-82, edited by H. Lehmann, Fortress, 1963): "If you are a preacher of grace, then preach a true and not a fictitious grace; if grace is true, you must bear a true [p.282] and not a fictitious sin. God does not save people who are only fictitious sinners. Be a sinner and sin boldly, but believe and rejoice in Christ even more boldly.... as long as we are here [in this world] we have to sin.... No sin will separate us from the Lamb, even though we commit fornication and murder a thousand times a day."(emphasis added).2. Letter 501 to Melanchthon: "Pecca fortiter, sed crede fortius." In the light of the standard version of the first item above, we render: "Sin boldly (or bravely) but believe still more boldly (or bravely)."
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Well, I asked for a quote and you gave me a quote, so thank you. I admit I'm not learned enough in this area to even try to explain it, (although I do note the breaks in text and the fact that the source is unfriendly to Luther's views.) However, it is what it is and I don't know the answer. The idea is just so strange to me that he would so openly refute something so plain in the Bible. I don't understand, I need to learn more about this.