What is the purpose of eternal Hell?

[SxyxS]

to make people believe in god-best marketing trick and pr ever.

"believe in God?"
-"no"
"why?"
-"no reason"
"damn.wait a momen.....I'll give you a reason.you will rest in hell if you don't believe"
-"I'm already in hell"
"but you will enter paradise if you believe in god"
-"deal.i believe in god"