The reply will be;
Dear So and So,
Thank you for expressing your concern for your child's safety. At the Catholic School, we place a high priority on the safety of your child. For that reason, no weapons are allowed on our campus. With the recent epidemic of school violence, it is important that this policy is upheld to preserve a safe educational environment for the future generations to grow, learn, and mature. Thank you for your thoughts.
The holy father, nun, pope, whomever
In other words, "are you crazy? NO guns are allowed. We throw rules out there that make everyone feel all fuzzy, warm, and safe, but they really do nothing to keep us safe."