Loyalty oaths were one of the major traps in european politics.
And considered objectionable on all grounds.
By their very nature, they are not taken by choice.
And that was demonstrated over and over with the "pledge of allegiance".
It's very use demonstrates what is wrong with the idea.
And it is extremely insulting.
If someone tried to hire you and asked you to take an oath not to steal from them, would you even consider the job?
Loyalty doesn't need an oath.
Oaths are often a part of indoctrination though.
That fact wasn't missed when this country was founded either.
The original pledge
I pledge allegiance to my Flag and to the Republic for which it stands, one nation indivisible, with liberty and justice for all.
Wikipedia
In 1940 the Supreme Court, in Minersville School District v. Gobitis, ruled that students in public schools could be compelled to swear the Pledge, even Jehovah's Witnesses like the defendants in that case who considered the flag salute to be idolatry. A rash of mob violence and intimidation against Jehovah's Witnesses followed the ruling. In 1943 the Supreme Court reversed its decision, ruling in West Virginia State Board of Education v. Barnette that "compulsory unification of opinion" violated the First Amendment.[6]

Students pledging to the flag with the Bellamy salute.
Swearing of the pledge is accompanied by a salute. An early version of the salute, adopted in 1892, was known as the Bellamy salute. It started with the hand outstretched toward the flag, palm down, and ended with the palm up. Because of the similarity between the Bellamy salute and the Nazi salute, developed later, President Franklin D. Roosevelt instituted the hand-over-the-heart gesture as the salute to be rendered by civilians during the Pledge of Allegiance and the national anthem in the United States, instead of the Bellamy salute. Removal of the Bellamy salute occurred on December 22, 1942, when Congress amended the Flag Code language first passed into law on June 22, 1942.
http://en.wikipedia.org/wiki/Pledge_of_Allegiance
http://en.wikipedia.org/wiki/Bellamy_salute
http://en.wikipedia.org/wiki/Criticism_ ... Allegiance
http://www.religioustolerance.org/nat_pled2.htm