I was listening to the Elena Kagan confirmation hearing today, and it began with the familiar oath-taking, ending with "So help you God". It startled me, because I was expecting the senator to say "So help YOUR God". The more I thought about it, the more this phrase, either way, sounded nonsensical to me. Does the oath-giver mean that he wants her to say, "I will tell the truth, therefore, help me, God!"?? It all sounds slightly archaic. So, help me, Martha and Grant!
I'm certainly neither Martha or Grant, so excuse my reply. You are right that this phrase is archaic. You could say it is a "fixed expression" which stands as a unit. Still, it can make sense when analyzed. Our contraversial friend, the subjunctive mood, makes an appearance.
"So help you God" effectively means "may God help you do it."
This use of subjunctive expresses a desire, wish, or hope. The so refers to the things that preceeded, the oath.
Does this make sense?
I agree that it is probably an archaic saying, but legal jargon, or phrases involved in legal processes, tend to maintain long after their meaning has left. My understanding -- and I do not have any scholarly support for this view -- is that the expression means that the oath-taker would be worried about punishment from a higher power if the oath-taker were to lie (i.e., sin). Thus, in the event of such a violation as perjury, only god would be able to save or account for the person. My understanding might be off, though. I think one way you seem to interpret it might make sense, too: that is, let god help me tell the truth.
By the way, I think the phrase properly punctuated is ". . . so help me, God." That iteration would lend more credence to either interpretation I mentioned above, I think.
You are right on target that "So, help me, God" carries a close meaning to "so help me God" using contemporary syntax and word order.
The best clue that this is not the underlying structure is the sister phrase "so help YOU God" which wouldn't make much sense as "So, help you, God."
It is not God who is being addressed directly, but the witnesses of the oath, for the "help me" version, or the oath taker, for the "help you" version. "God" is not in the vocative position, set off by commas, as in "Help me, O God." Rather, "God" is the subject of the verb. The word order is inverted because of the particular emphatic position of "so." (c.f. "So say I; so say we all.") The verb is not in the imperative mood, but in the subjunctive mood. No comma should be inserted between the elements, although the entire expression can be preceeded by a comma.
"So" stands in for all the preceeding promised actions.
"help" is the subjunctive mood, active voice, indicating a desire, hope, or wish.
"me/you" is the direct object — perhaps the most like contemporary use.
"God" is the subject of the verb "help".
"so help me God" = "may God help me do these things"
"so help you God" = "may God help you do these things"
Its root meaning is an indirect invocation of God's help to perform the sworn duties rightly. For some devout folks, it might carry the idea of a humble concession that it is not within their own power to do these things, and that they will need God's help. For others, it intensifies the seriousness of the oath, in that they are representing an intent to align their performance of the oath with God's will, and thus, their failure would be a sin. For still others, it is a fixed phrase that simply intensifies the seriousness of the oath.
Glenn said:
"so help me God" = "may God help me do these things"
"so help you God" = "may God help you do these things"
I'm more in line with tunawrites' analysis of the meaning. The phrase is not so much an invocation or request for divine guidance as it is an acknowledgment of the gravity of the agreement. The oath taker is being made to understand that he or she is entering into a covenant that will incur the wrath of God if broken. The intended meaning is closer to "may God smite me if I break this oath." This is what makes the oath of office an "oath" in the literal sense of the word: a sacred vow wherein divine agency is invoked as the guarantor of the oath taker's good faith.