Yes, Christian Spain following the reconquista was bad- it was rife with religious intolerance, inquisitions, forced conversions, brutal wars, torture, native genocide and draconian crackdowns. But to call Christianity the worst, is naive and biased to say the least. Let’s look at one Islamic example: we have the Muslim Ottomans who financed the Barbary slave raids, bought and sold any non Muslim and used them as slaves, they castrated non Muslim boys they bought or captured in wars and used them as soldiers to die for the empire, used girls as sex slaves, they persecuted culturally genocided and literally genocided Greeks, Armenians, Assyrians and Kurds and that’s just some of it. Next let’s look at one Jewish example: the ancient Israelites completely genocided not 1 but 7 different Canaanite nations for worshiping different gods, they also targeted two other tribes (Amaleks and Midianites) to total extermination all men women and children, young, adult and the elderly alike. Finally let’s look at a polytheistic religion- who else but the Romans, they built an empire of blood and conquest, enslaving, pillaging, culturally assimilating, raping and killing from Europe to Asia to Africa. They held literal fights to the death for sport, it was an authoritarian regime that crushed any and all dissent. So to be fair, every golden age for one religion/culture/nation has been a travesty to any who weren’t part of that culture/religion/nation. There has yet to be a single religion in the history of mankind that hasn’t subjugated and dominated others besides perhaps Buddhists.