The pledge of allegiance is a pledge to symbols and not to the actual ideals of the nation as they exist today or two hundred years ago. The preamble to the constitution is a pledge to ourselves and to each other and was written with the ideas that united and coming together we can accomplish more than the sum of our parts.
It is a promise to ourselves and to future generations that we will continue to act, work, and govern in good faith for the benefit for our nation.
Rather than declaring obedience to a static state we recognize that the work of government is work and that we will always be striving to be better.