I would hope that by now you have realized that I am not in the least afraid that my beliefs will not stand an assault. I also hope that you understand the difference between the beliefs of a mature adult and those of an impressionable child.
One cannot expect a child to sit in a public school classroom for over 1200 hours per year, for twelve or more years, under the powerful influence of schoolteachers, counselors, administrators and the like, and not be greatly influenced by the prevailing philosophies, values, morals and ethics of the public education system.
The public schools exert an enormous amount of influence on the minds and hearts of children during their most formative years. Add to the time spent in school the thousands of hours the average child spends in front of a television set, and the amount of time parents and Churches have to counter-balance the negative influences of the schools and the mass media is minimal at best.
Abe Lincoln once said, "The philosophy of the school room in one generation will be the philosophy of government in the next." That could easily be expanded to say, "The philosophy of the school room in one generation will be the philosophy of the nation in the next." The secular, humanistic, socialistic, progressivist philosophies of John Dewey and his disciples, instituted in the teachers' colleges seventy years ago, set in motion vast changes in our society that are ongoing even to this day.
It is my opinion, and I am in no way alone in my beliefs, that it was these very philosophies and those that they spawned, which have led our once great nation to the current sorry state it is in. Our educational system, once the envy of the world, is now a laughing stock. Our national morals have declined to such an abysmal level that Osama and his ilk can rightly call America "The Great Satan" because of the immoral filth that our mass media spews out to the rest of the world on a daily basis through television, Internet, magazines, movies, etc.
I could go on and on, but you have probably either stopped reading by now, or have "tuned me out" as a right-wing nut case.
In summary, the answer to your question "If you are so certain that what you believe is true, why are you so afraid that it won't withstand assault?" is this: I am not afraid. "Bring it on," "hit me with your best shot," yada, yada.
However, do not expect the same out of impressionable young children. To do so is both naive and ludicrous.