Some countries in the world grant what is called Dual Citizenship. They allow their citizens to hold the citizenship of another country, while retaining their American citizenship.
As a result, you will find, for example, many American citizens, many of them quite prominent ones, also holding simultaneously an Israeli Citizenship.
That is not considered a contradiction. And it is certainly not against the American Law.
Yet, here is an interesting fact about the process of acquiring American Citizenship -- Naturalization -- for Non-Citizens.
That is what it is called: Naturalization. It means all the steps that a Non-American-Citizen has to go through to become an American Citizen.
The final stage of this process is for a citizenship applicant, man or woman, who is currently holding a Non-US Citizenship to stand before a Federal Judge and solemnly swear to foreswear, renounce, reject and give up all foreign allegiances and citizenships.
Now, stop for a moment and think about it. Does it sound a bit like La Ilaha Illa Allah? First rejecting, renouncing and forswearing all other "gods," one might have had, before finally affirming one's allegiance to this one real God?
If it does, that is because that is exactly how it is. It is first saying "No!" to everyone else before saying "Yes!" to God Almighty.
Is the American Naturalization Process patterned after La Ilaha Illallah, I do not know. But does it sound and feel like it?
It sure does.