The universe can be eternal. It’s not metaphysically
impossible.
The problem is that a past-eternal universe is gonzo metaphysics and requires an
atheology which becomes more of a philosophical laughing stock than anything about God which atheists think needs mocking.
Example - In a past-eternal universe, so much ‘‘time’’ has already elapsed (an infinity of events,) that a single event in 2013 will not be unique, but instead will have already happened over and over and over and over
ad infinitum in the past. In an infinite past, there is an infinite amount of time for people to repeat stuff and invent stuff and learn stuff. It’s
Groundhog Day over and over and over and eventually Bill Murray has done everything an infinite number of times. So how long does it take him to invent a time machine and travel to 2013 to let us know that we are wasting our time thinking that the universe will come to an end - because it wont.
Atheists mock The Eternal God with divine, personal free will who can create and destroy but their alternative uncaused, past-eternal universe/multiverse is worse than
Camusian absurdity.