In his book A Rumor of Angels Berger recounts how the twentieth century had uncovered “the sociology of knowledge,” namely that people believe what they do largely because they are socially conditioned to do so. We like to think that we think for ourselves, but it is not that simple. We think like the people we most admire and need. Everyone belongs to a community that reinforces the plausibility of some beliefs and discourages others. Berger notes that many have concluded from this fact that, because we are all locked into our historical and cultural locations, it is impossible to judge the rightness or wrongness of competing beliefs.

Berger goes on, however, to point out that absolute relativism can only exist if the relativists exempt themselves from their own razor.9 If you infer from the social conditionedness of all belief that “no belief can be held as universally true for everyone,” that itself is a comprehensive claim about everyone that is the product of social conditions—so it cannot be true, on its own terms. “Relativity relativizes itself,” says Berger, so we can’t have relativism “all the way down.”10 Our cultural biases make weighing competing truth-claims harder, yes. The social conditionedness of belief is a fact, but it cannot be used to argue that all truth is completely relative or else the very argument refutes itself. Berger concludes that we cannot avoid weighing spiritual and religious claims by hiding behind the cliché that “there’s no way to know the Truth.” We must still do the hard work of asking: which affirmations about God, human nature, and spiritual reality are true and which are false? We will have to base our life on some answer to that question.

The Reason for God (Timothy Keller)