According to Christian theology, God desires for people to make the freewill decision to believe he exists and be in a loving relationship with him. Once people freely choose to accept Christ as their one true Lord and savior, the Holy Spirit is claimed to descend upon them to reveal the truth of Christianity in such a way that it is undeniable. Consequently, we would expect cognitive dissonance to never occur in Christians if their sincere belief is true. Nevertheless, one of the primary functions of apologetics is help Christians suppress the cognitive dissonance they routinely experience.In the field of psychology, cognitive dissonance occurs when a person holds two or more contradictory beliefs, ideas, or values, or participates in an action that goes against one of these three, and experiences psychological stress because of that. According to this theory, when two actions or ideas are not psychologically consistent with each other, people do all in their power to change them until they become consistent. The discomfort is triggered by the person's belief clashing with new information perceived, wherein they try to find a way to resolve the contradiction to reduce their discomfort.
In A Theory of Cognitive Dissonance (1957), Leon Festinger proposed that human beings strive for internal psychological consistency to function mentally in the real world. A person who experiences internal inconsistency tends to become psychologically uncomfortable and is motivated to reduce the cognitive dissonance. They tend to make changes to justify the stressful behavior, either by adding new parts to the cognition causing the psychological dissonance or by avoiding circumstances and contradictory information likely to increase the magnitude of the cognitive dissonance.
Coping with the nuances of contradictory ideas or experiences is mentally stressful. It requires energy and effort to sit with those seemingly opposite things that all seem true. Festinger argued that some people would inevitably resolve dissonance by blindly believing whatever they wanted to believe.
Once the truth of Christianity is divinely revealed to people by the Holy Spirit, it should be impossible for these Christians to hold two or more contradictory beliefs, ideas, or values. After all, their freewill choice to trust the word of God and acknowledge Jesus's sacrifice for their sins will have satisfied God's criteria for granting them the gift of salvation. As such, we expect there should be no theological purpose for God not to insulate his true Christian followers from experiencing cognitive dissonance now that he has assured their place in his kingdom.
At the very least, if Christianity is true, any secular beliefs that would seem to contradict Biblical beliefs should not be more compelling to a true Christian. However, the fact that Christians routinely experience cognitive dissonance demonstrates that the secular beliefs are often more persuasive than the Biblical beliefs they seem to contradict. Otherwise, we would expect an inability for those secular beliefs to routinely elicit experiences of cognitive dissonance in true Christians.
So, what are the apologetic arguments for why apologetics is needed to help true Christians suppress the cognitive dissonance they routinely experience given the aforementioned considerations? Why does apologetics not become obsolete after people become true Christians, but instead, it remains an essential tool for suppressing the cognitive dissonance they routinely experience?