The Supreme Court cannot overturn a Constitutional Amendment even when it is in conflict with another. They can interpret, that’s all. So, a simple amendment not imposing anything other than it is not a religion is what is needed. Once is is not a religion, everything else falls into place.
No amendment to the Constitution is simple in my opinion. Take the simple income tax amendment, or the 17 or the tenth, or the first, or second. We should have stopped at ten and gone no further.