"We don't go out on Friday night!"
Did you grow up in a non-observant home with that kind of inflexible rule, or are you the unbending parent who enforces it? South African Jews may not all be super-frum, but we pride ourselves on being traditional.
We Jews take pride in our intellectual prowess, boasting about our unusually high IQs and disproportionate numbers of Nobel laureates. Yet, Jews cling to traditions that they can't seem to rationalize. A modern secular Jew will often fast on Yom Kippur and will definitely give his son a bris.
In Hebrew, the word for laws (or traditions) that have no rational basis is "chukim". The word chokek (which stems from the same Hebrew root) means to engrave. Davka those things that we cling to without understanding are the ones that etch our Judaism into our hearts.
The human mind is a great asset, with the capacity to explore deep and abstract ideas. But, what you know in theory doesn't guarantee how you will behave in practice. History is full of stories of wise people who have made patently foolish errors. Judaism has survived through the greatest challenges of history not because of information, but because of dedication.
Torah knowledge is critical to keeping yourself and your children Jewish, but so is sticking to your traditional guns. The opener of this week's Torah portion (which discusses the inexplicable commandment of the "Parah Adumah", red heifer) is "Such is the chok (irrational law) of the Torah".
Hashem is telling us that what keeps Torah alive is specifically when we do those Jewish things that ostensibly make no sense, but link us back to centuries of tradition.