Aside from having to ignore much of what was written about the Constitution when "the people" (rich white males, mostly) were thinking about whether to vote for it (a majority probably voted against it, but that is another story), there is a big problem with the Fundamentalist Constitution:
Yes, it seems our Founders wrote socialism right into the Constitution, and it has been a specter haunting America ever since it was sent out for ratification on September 17, 1787.
The Framers of the Constitution actually thought government, including the federal government, could do some things better than private industry.
Let us enumerate them (mostly from Article I, Section 8):
"Provide for the common Defense" and "raise and support armies" and "a navy" [rather than hire out the job to mercenary private businesses]
"Establish Post Offices and Post Roads" [rather than contract out the job]
"the erection of Forts, Magazines, Arsenals, dock-Yards and other needful buildings," in the various States.
Let us call these things what they are: socialism. The government owning and running large organizations that are not essential to government itself. Anybody that thinks that our military is not a socialist organization has got a mental blind spot. Modern socialism of the authoritarian sort (Marxism Leninism) is largely modeled on military organizations.
But then, the real founding fathers had experienced and even studied reality, including the reality of mercenary armies. They were influenced by ideology (Thomas Jefferson more than others), but they were mostly powerful men, from powerful families, with plenty of school-of-hard-knocks experience. Think back to the Boston Tea Party itself. That gang of ruffians was not just protesting a consumption tax of the exact kind that Tea Party politicos like Herman Cain are proposing to burden us with. They were protesting against a private company, the East India Company. The tax was necessary, according to the British government, to pay off war debts. And what is our current vast national debt but a war debt?
Even in 1787 some things just made more sense to do through government, rather than through private industry. There are forms of Socialism that say a lot more should be owned and operated by the people through their government, and even forms of socialism that would have no government at all, but worker ownership of all businesses. I'm not saying any Framer was in that camp. They were, I repeat, pragmatic men.
Our Framers furiously debated the articles of the Constitution. Then the voters in each state debated whether to adopt the document. Socialism is not mentioned in the Constitution, but neither is Capitalism or the theory of free markets.
If some people, despite all the evidence of history, are against having a government that does its best to help its people cope with the difficulties inherent in reality, that is fine, we can debate that view.
Nothing they can do, however, can undo the fact that the postal system was a business specifically selected by George Washington and crew to be run by the government, for the people. That is not an all-encompassing system of socialism, but it is socialism as a pragmatic response to solving a particular human problem, the need for a postal system.