The subjects most easily deceived were told things like, “You know brushing your teeth is good for you, right? You’ve been taught this since you were little. Trust us.” When they subsequently heard arguments they never had before, this group felt sheltered and even deceived. The least vulnerable group were those who had not only been warned against a bad argument they would hear, but they were also taught how to respond. They were also warned they could face additional bad arguments and needed to be aware and vigilant. One thing we can learn from McGuire’s experiment is that the method many Christian parents and churches use to pass on the faith—reinforcement without taking counter ideas seriously—is the one most vulnerable to failure.
Many Christian parents worry about how best to pass faith onto their children. Tragically, statistics suggest they are right to worry. In 2020, the Cultural Research Center at Arizona Christian University found that just 2% of millennials, a generation now well into adulthood, have a biblical worldview. That is the lowest of any generation since surveys on the topic began. According to a Lifeway Research report , two-thirds of those who attend church as teenagers will drop out of church as adults.
A significant aspect of the battle for the hearts and minds of the next generation has to do with ideas. Helping students think correctly about life and the world, God and themselves, would be hard enough if they weren’t also facing such strong cultural headwinds. Simply put, many young people today leave the faith because they lack the necessary immunity from the bad ideas of our culture. Christian parents must not only present truth to their kids; they must find ways to immunize them against lies.
Dr. William McGuire, a Yale psychology professor in the 1950s, suggested that bad ideas behave like viruses. Specifically, he thought that the more exposure one has to bad ideas in a controlled setting, the less likely they are to fall for those ideas later. McGuire performed several experiments in which he tried to convince subjects of a lie, that brushing teeth is bad for them. Unsurprisingly, those given no preparation for what they were about to hear were more easily convinced of the lie than those warned against a specific bad argument they would hear.
However, the subgroups that were the easiest and the hardest to dupe were surprising. The group most vulnerable to falsehoods was not the one with zero preparation, but the one who had merely had the truth reinforced.