If life is just the result of spontaneous generation like the scientists believe then it is imperative that any intelligent species that pops up has a very limited time to escape their original planet. A few hundred years into technologically advanced industrial existence and everything is used up. Thus the need for a new planet.
But there's a problem. Bio-organisms. Like viruses. In order to survive on a new planet the colonizing life forms must co-mingle their DNA with some suitable resident species.
If Somebody made up the Bible out of whole cloth then something like the above could be a reasonable explanation for what's going on around here.
They MUST?