But do you think that we should still be following the same set of ideas as we were centuries ago? Sure, there may have been a lot of famous documents and people who mentioned god in their text, however, is it right to single out a certain god (or generic god for that matter) in our country's documents? What if I was polytheistic? It might upset me.
Not to mention that these people, speaking of god in their speeches, perhaps were also just practicing their freedom of speech. But should anything pertaining to law be in any way related to god?