There's two very different characters here, trump and his audience.
Trump is a spoiled brat who never grew up, who honed through a lifetime of pitiful scams and his reality show a notable talent for manipulating minds stuck in molasses. Even those of us who aren't acquainted with exactly such a person have surely known of separate individuals with portions of that personality, esp. back in school before we had the freedom to choose different paths in life.
Trump's audience are possessors of the said conservative "old ways are best" brain, which I think most have at least met here and there. Though such a mindset acts as natural defense against nouveau whimsy, it becomes a liability in modern times where reality has typically done parted ways with tradition. This is a key point, since ostensibly in a more idyllic time it would've been liberals whose ideals about progress would've been fanciful. So these people are mentally still living in a past that's no longer the case, when they had social status by birthright---some combination of white, male, american, middle class, etc.
To connect these two, the approach of the con artist in this situation is simply promise a return to that world, back away from modernity, where the audience won't have to be considered equals of the opposing foreigny ethnic types under the patronage of liberal elites. Notice what they most instinctively fear is that very archetype. It also helps that trump's projected image is the perfect embodiment of what they aspire to: rich old paternal merican rather proud of himself. They will gladly cast away jesus or whatever other flimsy rationalizations for what's really important here.
Viewed in this context, his well-aimed speeches and the reaction they garner from the audience make perfect sense.