It's speaking of the Christian God unless anyone can just substitute their God in that place? Under Shiva? Under Mohammed. If it cannot be substituted because they are speaking of a particular God then yes, it is a violation and should be removed. You cannot make a preference for one God over another.
Using the term "under God" is offensive to agnostics and atheists. Not everybody in America believes in a supernatural spiritual authority. America is a multicultural nation, and there needs to be respect for all belief systems. This is true for Christians, but it is also true for atheists and other non-beleivers.
I personally feel that in the country of origin it is merely ceremonial, but when you get a group of people from other countries that have their you need a approach by which people understand that as a ceremonial antidote or clarification or regardless of today’s views in the time of building this Great America “Under God “ is what helped us prevail and there is only a couple of words that transcend over into one language God is one of them, also if you start taking down your only stronghold what kind if country do you stand for. It is only to remind us of our "Overcoming" in a time of war. Instead of giving oath to a person we give it to “God”.
You do not need to say the Pledge by any stretch of the imagination. I, personally, omit the word "indivisible" because I will not pledge myself to an indivisible nation. So, you have the Right to Association, so you can associate with the Pledge, or a part of it, or you can chose to not associate by saying it. Saying the Pledge is a choice that you make.
The only way that your right is violated is if you opt to say the Pledge.