Genghis Khan gets a bad rap. His negatives have been mostly related by Medieval Europeans who were about as close-minded and backward as any society in history. In contrast to the stories Europeans told of Mongol barbarians–Europeans didn’t travel much except to the Middle East for the purpose of slaughtering Jews and Muslims–Khan’s Mongols were exceptionally progressive.
Genghis Khan was open to all religions being practiced under his rule, which by the way extended from the Pacific Ocean in the east to Europe in the west. Consider a nation unified by a comparative handful of horsemen that includes China, Russia, central Asia, the Middle East, and Europe. That takes a lot more than brutality to pull off.
Genghis Kahn, and many of his heirs, ruled with political shrewdness, military accuracy (the Mongols often fought much, much larger armies), and considerable benevolence. Khan treated his enemies with respect; if they surrendered, they were welcomed into the empire. He abolished torture. He shared the spoils of war equally, preventing both hoarding and looting. He established communications, trade, technological transfers, and a single financial system from one end of the empire to the other. He promoted military and political leaders on the basis of merit, rather than familial relationships.
He, and his fellow Mongols, worshipped The Eternal Blue Sky, a universal spirit that encompassed all life and nature. I can say after having been to the steppes of Central Asia, Mongol beliefs make a lot of sense.