The constitution was an attempt to correct the deficiencies of a failed confederation of the States which was established after we won the war of independence. Consider it our Second Republic. The Constitution tried to strike a balance between federal and state power and between the concepts of pure democracy and indirect democracy (hence the House and Senate, and the Spearation of Powers. The people who conceived and wrote it understood it was an imperfect document and thus created a means by which it could be amended, hence when "original intent" was that women could not vote and that slaves counted as three fifths of a person, there was room to change that, which has happened. As for religion, at the time various states favored different religions. Maryland for example was heavily Catholic, other states were Anglican, Puritan etc., the idea of the First Amendment was to allow for the practice of any religion without interference by the government, and the purpose of the applicable portion which set forth the criteria for qualifications to hold office was specific in that it said religion could never play a role in anyone's ability to hold office. Many of the founders were not even Christians. They were deists.