I pledge allegiance to the flag of the United States of America and to the Republic (not Democracy because we aren’t a Democracy) for which it stands, one nation UNDER GOD, indivisible, with liberty and justice for all.
I've always liked the ‘one nation under god’ part because it establishes a hierarchy. There is a nation to which we are pledging allegiance to, but it is under god. It is lesser than god. God outranks the nation. You are pledging allegiance to the nation but it isn’t a blind allegiance. Being true to god, whatever god that may be, and the nation can’t even tell you what god you are allowed to revere so it is completely up to you, is seen by the nation as more important than allegiance to the nation.
If you say there is no god then nothing fills that role. In that case, do you believe there is nothing above the nation? Is the nation the highest authority that exists for you?