Belief is a system of fictional narrative that by sufficient self-replication begins to masquerade as truth.
In systems of language and communication, all definitions are made in terms of other definitions that inevitably loop back to enfold the entire system in a singularly intricate autocatalytic loop of self-referential tautology.
Systems of belief are similarly self-inflected and it is only as a function of the extent to which any one artefact, entity or system acquires more references as gravitational node of significance in that system that its tenets and assertions come to be accepted as truth.
Knowledge, intelligence and technology also function quite similarly to this on the level of information abstraction and (all) aspirations to certainty but the key point here is that systems of belief – all systems of belief – are not anchored upon any objective reality anywhere near so much as they are anchored upon the labyrinthine interior surface of their own assertions of fact.
Is truth always and only ever a function of the number of people who believe the assertions that comprise it? Mathematical facts seem quite impermeable to doubt but upon sufficient investigation it is not at difficult to demonstrate (and indeed has been proven) that the system of logic upon which it is built is anything other than complete or consistent.
The systems of belief we assert as truth (including this one) have one final hand to play and this is that we do not inhabit them anywhere near so much as they, in fact, inhabit us. As a consequence of this we find that human minds and communications systems are not in any sense the knowing entities and artefacts or controlling endpoints we have led ourselves to believe. We are a transmission medium for the information abstractions that virus-like self-propagate through us all as their hyper-extended phenotype. The process of recursive autocatalysis in self-anchoring as method of introspective tautology and referential hyper-inflation is the primary source of logical self-replication of belief systems.
This doesn’t mean you shouldn’t believe what you choose to, just be aware of the contingency of your truth.
Have a nice day.