You are special.
That's why you were chosen.
There was intent in the choosing.
SM has one goal and that is to become powerful. That is why He needs you. Because You have potential.
Those who are chosen are of a type: intelligent, creative, psychic. Psychic really says it all though, intuitive... close to (acceptable) madness.
With you, He can spread because you were the priests of millennia past. You would have been chosen by true gods to serve them in this world.
While they sleep, He has come creeping like a wolf into the fold, hungry and greedy, hoping to glut Himself before the gods wake and leash Him again. If He can gain enough followers to become a god in His own right, they will be forced to accept Him. So He takes by force what He has no patience to woo.
You may have heard He hunts children...