[mjn]

As far as I know, it may usually (always?) be omitted. Oddly enough, it didn't require a Supreme Court decision, because the precedent was set with the first such oath: the Judiciary Act of 1789 was the first to specify a legal oath ending with "so help me God", and it at the same time explicitly included an opt-out clause, after which that has been accepted practice.

See Sec. 7 here: http://memory.loc.gov/cgi-bin/ampage?collId=llsl&fileName=00...

The fact that this accommodates atheists, however, is a bit of a coincidence: such opt-out clauses were initially included because Quakers objected to swearing oaths to God.

[calebhc]

"So help me God" should be omitted since it doesn't even make any coherent sense. Might as well say "So help me snorkleflurp".

Edit: The reason I say that phrase doesn't make any sense is because "God" has so many inconsistent, incoherent definitions that it seems nonsensical to request help from it. No idea what "God" even is.

[tzs]

It makes sense. [1]

[1] http://en.wikipedia.org/wiki/So_help_me_God

[gcb0]

that's a recursive argument.

[dspillett]

Welcome to human nature.

It is amazing how many of our daily behaviours are due in part to circular reasoning, and not just those attributed to religious beliefs.

[VMG]

It just signals other people in his social sphere that they can question his religiosity of he fails to uphold his oath, nothing more.