http://en.wikipedia.org/wiki/Pledge_of_Allegiance
The Pledge has been modified 4 times, all 4 required Congressional approval.
The addition of the words "under God" were the latest being introduced by Ike and approved by Congress.
That makes is come close to falling under "law".
Problem I have with this in The Pledge is that some folks who feel as strongly about their religion as the believers in God, as in the Jedeo/Christian God, believe in theirs, are forced to either not pledge to the country they love or make a compromise and remain silent for that passage while still participating in an act that acknowledges another "god"
God, being the jealous God he is, might take exception to that.
While I expect adults to be able to handle all this without to much suffering, I do consider it different for children.
With children being so tolerant of kids who are different in almost any way, those who don't believe in the J/C God should receive little hassle or rejection when they sit out the pledge or clam up for that passage.