First off, like many others here I have served my country with pride for over 24 years and am now retired. I too pledge this allegiance when I was in school. I'm not now, nor have ever been a very religious person, but don't discount the possibility of a higher power.
The Pledge of Allegiance in my mind is a tool, used by the government and the people of this great nation to encourage patriotism and to help people appreciate the life they are allowed to live. It is nothing more than that. As far as the two word "under God" having been inserted it really doesn't matter to me whether or not they are taken out. The reason they were put in is well known.
My main point is that I do not believe that these two words (which can be substituted if you're of a different religion), in my opinion, breach the separation of Church and State. To do that these words would have to empower one or the other to have the means to effect how the other governs itself. These words do not do that. They do not give the Church any power over how the government is run, nor do they give the government any power over how the Church is governed.
As for the word God, I believe it was used because at the time of the insertion, we (the USA) were a predominately English speaking nation and all of the religions that I'm aware of from English speaking nations all refer to a higher power as God. If we would have been a predominately Arabic speaking nation, for example, at the time of the insertion, then I'm sure that it probably would have been Alla that was inserted instead.
I would also like to state that I am not making these statements to start a flame war and tried to word it in such a fashion that I did not offend anyone. I simply wanted to state my opinion, for which I have given over half my life to protect the freedom to do so.