god smites all non believers with eternal hell fire where you scream and burn and melt and have your eyes gouged out for a million eternities until you turn to ash, and then you are are reconstituted into penis meat that you yourself are forced to gorge upon until your innards burst, spewing bile and decomposed cock flesh onto the bone riddled floor of the inferno until the sun turns black for the 666th time but he loves you and he needs money
Its to remind you that your time on earth is limited. its a time of reflection that you are not immortal. when they put the ash on you they say "remember you are dust and to dust you shall return".