Vaccines operate on the principals of inoculation. If you give a small amount of an inactivated or harmless version of an infection, you build up a resistance. Well, theology is a vaccine for reason! It has all the hallmarks of reason, without the reason. It allows one to hone one’s rationalization in a protected environment surrounded by other believers, so that it has its virulent effects like doubt and independent thought are removed!
(As a side note, this takes on a down the rabbit hole quality when you consider that nonreligious parents do exactly the opposite of this in allowing their children to believe in things like Santa)