What gives a religion the right to claim their fantasy is correct and the rest false?

[vorlon13]

For the early decades/centuries of Christianity, there wasn't a bible, manual, users guide or website to go check.  Word of mouth is how it spread, and congregations were on their own in regards as to how they were going to interpret the 5th, 10th or 20th hand version of the Christ story they heard in their specific village.  

This unsystem would guaranty all manner of HIDEOUS and VILE blasphemies and heresies to spread like cancer, and literally no 2 of the early churches would have been hewing to the same actual beliefs, and you're looking at total chaos dogma wise.  And since these early churches were populated with unavoidably illiterate congregations who left precious little of a paper trail, or even a simple count of how many of them there were, the true number of Christian denoms would be significantly larger, but even a guess about the actual number would just that, a wild guess.

 Though your assertion regarding diversity in the Early Christianity and non-existence of the canonical list of scriptures is evidently true, it stays unrelated to the argument I raised above.
It doesn't matter how diverse Early Christianity was, or what subjects they (dis)agreed upon. What matters is that almost every christian-based religion today accepts the Bible as divinely inspired book. That supposedly divinely inspired book tells us explicitly that the Church was established in the 1st century AD, as well as that its existence would prolong until the Second Coming (though this interpretation might not be perfectly true from ecclesiological standpoint of many traditional churches [e.g. Roman Catholic, Eastern Orthodox, etc.], it provides a necessary and sufficient basis for our discussion here, and is evident from the text itself). 

Therefore, the argument in a form of syllogism goes as follows:

P1: genuine Christian church exists from the 1st century AD (X) and will last until the Second Coming (Y).
P2: most of the 70,000+ christian-based religions don't exist from the 1st century AD.
C: most of the 70,000+ christian-based religions don't possess at least one conceptually necessary property (X) that genuine Christian church possesses according to the Bible.

Or, regarding the n existing churches in the 1st century AD:

P1: genuine Christian church exists from the 1st century AD (X) and will last until the Second Coming (Y).
P2: most of the n existing churches in the 1st century AD don't exist today.
C: most of the n existing churches in the 1st century don't possess one conceptually necessary property (Y) that genuine Christian church possesses according to the Bible. 


It goes without saying that this is no evidence of any sort, since the first premise is dependent upon one's willingness to accept the Bible as divinely inspired book. This argument works specifically under the assumption that one accepts said claim, either truly or for the purpose of debate. Thus, though my conclusions are by all means logically valid, they are not necessarily true.

God gave His Word for no other reason than it would be kept.

Don't overthink this.