If you had been born in Saudi Arabia you would be Muslim, and if you had been born in Thailand you would probably be Buddhist. Your Christianity is an accident of birthplace, not a discovery of truth — so why trust it?

Why people find it persuasive

The strong statistical correlation between geography, family, and religious identity is well documented and intuitively troubling — it looks like belief tracks accident of birth more than evidence.

Important distinctions

• • The sociological fact that upbringing strongly influences which religion one is exposed to and initially adheres to vs. the separate epistemic question of whether any particular religious claim is true.
• • Belief formed by upbringing and never examined vs. belief formed by upbringing but subsequently tested, and either confirmed or revised, by adult reflection.
• • A genetic critique applied selectively to religion vs. applied consistently to all belief formed under similar conditions, including irreligion and specific irreligious commitments.
• • Correlation between geography and religious label vs. correlation between geography and considered adult conviction after examination.

Christian response

• • This is a species of the genetic fallacy: the causal origin of a belief (how you came to hold it) is logically independent of its truth-value (whether it is in fact true) — a mathematician who first learned arithmetic from a parent in a particular country does not thereby have less reason to trust that two plus two equals four.
• • The argument, applied consistently rather than selectively, cuts against every belief with geographically and culturally patterned distribution, including irreligion itself: had a given secular Western critic been born in 1940s Soviet Russia they would very likely be an atheist for reasons of state ideology rather than reasoned conviction, and had they been born in a devout household in rural Poland at the same time they would very likely be a fervent Catholic — the genetic point applies to every worldview equally and therefore functions as a universal skeptical acid that, applied consistently, would corrode confidence in any belief whatsoever, including the belief that geography determines belief.
• • The relevant question is not how a person first came to consider a claim but whether they have since examined it on its merits as an adult capable of independent reasoning — many committed Christians (C. S. Lewis, raised nominally and becoming an atheist before a reasoned adult reconversion; Francis Collins, raised with no strong religious formation, converting as an adult scientist) arrived at their convictions well outside, or well after abandoning, their upbringing, just as many raised Christian have examined the claims as adults and rejected them — showing that upbringing, while a powerful initial influence, does not straightforwardly determine adult conviction.
• • If geographic and cultural distribution of belief were sufficient by itself to defeat a belief's truth-claim, it would equally defeat the belief, common among the very people making this objection, that human rights, liberal democracy, or scientific materialism are true, all of which are also unevenly and unequally distributed by geography and culture for broadly similar sociological reasons.
• • Christianity's own missionary and apologetic tradition takes this problem seriously rather than ignoring it — it is precisely because belief is not self-validating merely by being widely or locally held that historic Christian apologetics (from Justin Martyr in the 2nd century to contemporary natural theology) has always tried to argue for its claims on independent evidential and philosophical grounds addressable to anyone, of any birthplace, rather than resting the case on cultural inheritance.

Christian counterresponse

That counsel of humility is well taken and should be applied evenhandedly by believers and skeptics alike about their own inherited convictions, but humility about the reliability of one's belief-forming process is compatible with, and does not by itself defeat, a belief turning out to be true and reasonably held on independent grounds after honest reflection — the two questions (how confident should I be in my own reasoning, and is the claim actually true) remain distinct.