I'm not aware about a "common" belief, I'm going by the universe always existing as HP Pythia said.
This whole topic about the universe and its origins or how our Gods came to be isn't important in Satanism.
Mainstream religions focus much on creationism because they are based on blindly worshipping a being who they think it's all-powerful and created the universe and controls everything, but that isn't the purpose in Spiritual Satanism.
Zevism's main goal is to work with the Gods who help transform ourselves and humanity into Gods, like them. Zevism don't look to blindly worship a being who is supposedly powerful, but to our Gods because they are the only ones who help us develop our souls and become like them. Their personal background isn't important, the knowledge and guidance that bring to us is.