In the past, I have argued against "under God" in the Pledge of Allegiance and a national motto of "In God We Trust" as a moral issue.
The former equates atheism with rebellion, tyranny, and injustice and, as such, represents a bigoted attitude towards those who do believe that no God exists. The latter embraces a principle that governments may declare that its preferred citizens trust in God.
However, if I were to raise a legal objection against these practices, I would not ground it primarily on the First Amendment separation of church and state. I would instead ground it on Article 6, Section 3:
The Senators and Representatives before mentioned, and the Members of the several State Legislatures, and all executive and judicial Officers, both of the United States and of the several States, shall be bound by Oath or Affirmation, to support this Constitution; but no religious test shall ever be required as a qualification to any office or public trust under the United States.
Because the intent and the effect of having a national motto that says "In God We Trust" and having "under God" in the Pledge of Allegiance is to create a de-facto religious test for public office.
In the case of the pledge, it is particularly relevant that the Constitution mentions that no religious test should be made a part of an oath or affirmation – or, we may assume – a pledge of allegiance.
Quite a few supporters of secular government demonstrated just how politically naive they are when they declared the recent passage of a resolution affirming "In God We Trust" as the national motto to be a waste of time. It was not a waste of time. It served a political purpose of reserving seats in the House of Representatives exclusively for those who trust in God. Or at least exclusively for those who refuse to admit that they do not trust in God.
"Vote against this resolution - reject the claim that America's preferred citizens trust in God - and we will use this against you in the next election. Seats in this body are reserved exclusively for those who affirm that America's preferred citizens trust in God."
How many affirmed atheists are running for public office in 2012?
One reason is obvious. They know it to be a waste of time. They know that government has effectively established a de-facto religious test for public office and they do not qualify.
"Under God" in the Pledge of Allegiance is an even more effective religious test.
Let's have a candidate run for public office while refusing to say the Pledge of Allegiance. Gerrymandering and partisan politics have created a few districts in which it may be possible. However, as a matter of fact the government has set up a system for effectively barring people who do not support a nation "under God" from holding public office.
A filter that is "only" 99.8% effective is still a filter.
It is also important to note that most people will take the fact that a candidate refuses to say the Pledge of Allegiance as evidence, not that he is an atheist, but that he professes no allegiance to America. The Pledge instantiates the attitude that atheists are, by that very fact, anti-American.
No power can prevent the people themselves from applying a religious test when they vote. This is true in the same sense that no government can prevent a person from voting for or against a candidate on the basis of race or gender.
However, this does not give the government authority to embrace or endorse those bigotries – as it does when it embraces a motto of “In God We Trust” or a pledge containing the words “under God”.
If I were standing in front of a judge arguing against "under God" or "In God We Trust," I would certainly mention the First Amendment arguments – briefly and in passing. However, I would spend the bulk of my allotted time on the "No Religious Test" argument. And my client would not be some parents of a school-age kid going to school where the Pledge is recited. My client would be an otherwise well-qualified candidate for public office.
One advantage of this tactic is that I can answer the judicial challenge, "Isn't this an issue best left to the legislature?" The answer to this being, "Not if the legislature is using this to stack the legislative deck in favor of those holding certain religious beliefs." This requires a judicial remedy - and the Constitution demands one as well.
We seem to have a lot of atheists out there eager to file lawsuits on things as trivial as a cross on government property. I would suggest filing this lawsuit instead. File a lawsuit to end state-sanctioned bigotry against atheists by using the national motto and Pledge of Allegiance to establish an effective religious test for public office.
Then, just maybe, we can actually stand a ghost of a chance of getting more than a token atheist elected to public office.