How many ancient works of literature say that the universe had a beginning?
How many atheist scientists do you think said it had a beginning, before Einstein said it?
None.
Universally through out the world the belief was that our universe and time stretched infinitely into the past. Now we know better. It had a beginning. Only one work from antiquity claimed that light, space and time came into existence suddenly as the creative act of a supreme being.
The book of Genesis.
Today scientists and atheists are so disturbed by the implications of this truth that they perform mental gyrations and speculate it happened as the result of fluctuating quantum foam, whatever that is, or some other pipe dream.
Multiple universes is their current idea.
Theorizing multiple universes is like theorizing about what happens to the soul when a human mind ceases to function.
There is no way to affirm or refute any idea that floats their boat.
Very convenient.