Perhaps, the tendency to leftism yields extinction, due to falling birthrates that are a chronic side effect? We see that all over Europe. Where the most popular male baby name in every city of merit is now "Mohamed".
You don't just abandon your religion, and become Atheist. There is no place for Atheism. When a nation rejects its religion, it doesn't become secular. It becomes a vaccuum. And a more robust religion fills that vaccuum.