Why not? He has repeatedly made pro-Christian statements from the bench - he's rather famous for them as a matter of fact.
it would be Judaism.
I wouldn't want a Torah on the door of the courthouse either.
Because an unlimited, endless stream of pro-Christian (whatever that means) statements by the Chief Justice of Alabama, or by the President of the United States, is not an Act of Congress and does not constitute an establishment of religion.
The vast majority of Americans are Christians, and are called to vocally and publically profess their faith and attempt to convert others.
This free exercise of religion is constitutionally protected, and establishes nothing.