What does the metaphysical belief of atheism entail?
It doesn't entail a belief that the universe has no purpose much less that it's meaningless.
It doesn't entail a belief in metaphysical naturalism.
It doesn't entail a denial of the paranormal or a spirit world or even a life-after-death.
So what exactly follows from atheism?
What follows from atheism is the denial of theism. Atheists believe that it is not the case that "At least one God exists."