Earlier chapter Satan himself stated that MC is a low ranking devil but somehow obtained power of a high class one(Probably cuz he persevered and ate other devils in the war).Seems like after Zeus (name of God in this) destroyed most devils he and Satan has a ceasefire and wager the result on the war on MC to see if he will be good or not (Also Ars was implied to be the hero of this world ,who will be the one who kill the MC ,in same chapter by God)