Is it true that Martin Luther cursed a lot and even used some bad language in his own writings?
It should be noted that profanity is a relative cultural concept. That is, what one culture considers to be profane may not be offensive in another. For example, various hand gestures that are perfectly acceptable in the USA would be highly offensive in the Middle East. Similarly, the word "bloody" in the UK carries a harsher connotation than in American English. Thus we should not be quick to dismiss quotes because they do not match what our culture considers to be profanity, especially in Western culture that allows horrific words, violence, and sexuality to be displayed routinely on public television. With this in mind, I offer some quotes by Martin Luther:
"Did I not tell you earlier that a Jew is such a noble, precious jewel that God and all the angels dance when he farts?" (On the Jews and Their Lies)
"He who hears this name [God] from a Jew must inform the authorities, or else throw pig poop at him when he sees him and chase him away." (On the Jews and Their Lies)
Of course "fart" was highly offensive at the time and "pig poop" (older translations say "sow dung") can be translated more harshly - I don't think I need to spell it out ;)
Yes it is, Martin Luther was after all: angry and upset at the Pope and the Catholic clergy. Some examples would be: "no sooner do I pass a motion than they smell it in rome. Saying in effect that Rome was a cess pool. Many times does he call Monks the "lice placed by the devil on God's almighty fur coat." There are of course many other things I won't repeat out of decency.
Martin Luther also would curse Rome and the Pope, comparing them to villains in the bible. These phrases of themselves are not "extreme" by todays standards of course, however when the remarks were made they were directed at the Holy men of the time, something many people just thought as heresy. So it's easy to believe that a lot of the things he said were taken to be just so foul.