The rise of the Elder Gods, and especially that of Cthulhu, has been associated with the end of the world since H.P. Lovecraft first described the writings of the Mad Arab. In the intervening years one thing has become glaringly obvious.
There is no rapture for believers. Total destruction of humanity is the purpose.
However, some might suggest that being raptured by Cthulhu might not be as horrible as it seems. Ben Hopper is one.
There is no word yet on the return of the Old Ones.