Because you'd need a ladder to reach the top of the legal code, and once done you'd have already perjured yourself, with all the waste, fraud, redundancy, & bipolar (self incriminating, recriminating) laws contained within.
A document written (perpetually), to facilitate the requirement/need for lawyers to then do battle while plugging the Court system for eternity with red-herring issues (but they're still getting "Royally" paid), and accomplishing nothing, since no-one knows what's in it any longer.
One might call that Cancer.
Do you want to pledge allegiance to a malignant tumor instead?
How "Typical" of you to denounce, yet offer NO replacement.
Do you have an idea, or are you just crying?
(this may be a blow to that ego your teacher pumped-up with pats on the head, but ...)
Take a number, you're not First.
edit: You are correct, God does not appear in the Constitution (they were careful not to do so, epic denotation of intelligence, foreseeing future attacks based solely upon that issue)
Yet it does say "as long as it doesn't interfere with the rights of others".
I believe that being taxed/billed to pay for $800 a night prostitutes from a Colombian brothel, for security guards, for an inebriated, vacationing official ...
(indirectly with well padded expense accounts & no paper trail)
is "pushing it" beyond the abyss.
Either way, (there's no question) the people we have, don't measure up, to what the Framers envisioned.
They now believe themselves to be the (all but) permanent Nobility of a New-Feudalism, reincarnated.
What document they "pretend" to swear upon, is as credible an act, as a promise from my first-wife.