Christians also feel critics of Christianity don't understand what it is, despite apostates consistently scoring higher than them on Biblical literacy tests.
There's a sensible reason for this: Religions look drastically different from the inside than they do from the outside. So, an outsider describing what a religion looks like to him will sound ignorant to believers, who take it at face value rather than reading between the lines.
If you were in that boat, how would you know it? It wouldn't be obvious to you, unless you're smarter than every religious person ever to live. Very clearly they are designed to appear convincingly as sober reality to those in the fold, otherwise religions wouldn't survive for long. But here are some red flags you might look for:
✓inherited ancestral sin
✓absolution only by conversion
✓roots worldview in subjective feeling which can't be examined/argued with
✓claims to be exclusive arbiter of morality
✓dissent is an act of violence
Steve Hassan's B.I.T.E. model is also an instructive basis for comparison.