I haven’t seen the actual oath, but I don’t think the point is to call parents “perfect”, but rather to actually address what Catholicism is, and let people know what is expected of them and their children, as Catholic Christians.
So, if some parents are not validly married (not necessarily in the church, as we do recognize Protestant-Protestant marriages and the parents may be converts and not yet have convalidated their marriage), by their oath they are going to try to live the teaching. If they aren’t validly married, they will try to be so, and if not able, will live as brother/ sister.
If some parents are contracepting, they will repent (can’t change the past, but then again we aren’t talking of the past), and not contracept in future.
If some parents cheat on their taxes, they’ll make restitution and sin no more.
Etc., etc.
And, if they can’t make that choice, they won’t sign the oath and they won’t enroll the child in school to get a Catholic education that they themselves, by their freely chosen actions, fail to support in the home.
We have seen, I think, that a Catholic education is not to be considered a “given” or a “right”–that, in fact, it carries with it certain responsibilities. One of those responsibilities is that the education is not just given in school, but lived at home.
Putting a child in a position where s/he is taught the truth in school, but not at home, is wrong IMO, just as it is to have him/her taught the truth at home but not in school. Why has society changed so much in 50 years? Look at the incontrovertable fact that education has changed from the Judeo-Christian tradition that was found even in public schools to a secular humanism that is far removed from the education most parents remember. “Values based” teaching puts everything into a relativistic, situational perspective, with children encouraged to think “critically” and with no absolute criteria to ground themselves.
It’s a long way from: Is action X good or bad? to the current, “given action X, considering the situation, the participants, and your own personal bias or hangups, good–speaking, of course, for you personally?”