Originally posted by Thrawn
Why?
Because it's inconsistent with existing laws.
"God" shows up all over. As has been stated in other posts... money says "In God We Trust", witnesses in court swear in with "so help me God," etc.
The Supreme Court will fight the fights that are worth fighting. In the broad scope of things, this one isn't important and to make this one stick, they've got a whole lot of other laws that will also have to be changed.
The Senate will go along with it because the vast majority of the people in this country consider themselves to be Christian.