“Mathematics would certainly have not come into existence if one had known from the beginning that there was in nature no exactly straight line, no actual circle, no absolute magnitude.”
Many Christians were offended by many of the statements of Friedrich Nietzsche. He took some glee in it, but also, he spoke in ways as to be sure he had the attention of his listeners (readers.) He did indeed say God is dead. Some took this to mean that Nietzsche was saying that he should be dead, or God was a concept that never worked. But if you read his words he is saying something else by it. God is dead, so now we must rise above the morals that come from a religious context and create that of human views. We must create the higher man. This led the world to an idea called Nihilism that when combined with Nietzsche some believe is the equivalent of saying nothing matters and nothing ever did. I don't think this is what he was saying at all. Nietzsche was a person who saw religion, Jewish, Christian, Muslim and more as being a way of holding back the vulgar side of human instincts. That wasn't bad, but if it did that, might it not also be doing the same on the other end of the spectrum. I believe he was saying, we have to kill our gods and beliefs, so that we might rise above the limits of religious faith.
I believe that Nietzsche would have been sickened by the use of his concepts. Those who hated Jews didn't perceive how he was using the Jewish people not in hate but as an example of a foreign group entering the majority group, and having its values overcome the larger group. Instead Anti-Semites took the words without understanding the greater concepts and tried to carry them like a banner. But Nietzsche himself told his Jew hating sister to stop it, and was disgusted by Richard Wagner's virulent hatred of Jews. That Nihilism blossomed and Nietzsche is associated with it is again something that he would have hated. Nihilism suggests that there is nothing. Nietzsche suggests that there is much to hold high and exalt. That we must find and prioritize those great things, instead of gathering around the fire singing to gods who he felt were useless. I am not even sure he did or did not believe in a God or gods, he just felt them to be unnecessary to existence of what he hoped would become the future of the greater man.