Mob violence has been a thing for all of human history. Before humans, even: chimpanzee groups, if they get large, will split into two groups. After a few months apart, if the groups encounter each other, the stronger group will murder every individual in the weaker one.
I think we had settled on a regulated and normalized system in pre-internet media that moderated the mob violence tendencies. Our current polarization is not really that social media created this new thing in society, it’s that it removed the guardrails in traditional media that were suppressing natural human tendencies. I hope we can figure out and implement some new guardrails sooner rather than later.
Before it was collected as a compendium of official parts, sure, but most of the individual books (both the ones that made it into the current version and additional ones that ended up being rejected) were around. The Old Testament ones were already written down, and most of the Gospels were at least oral tradition very early on.
I believe it was over one hundred years before the Gospels were all written down, and early Christian sects had passionate disagreement over which texts were official or hearsay, but it’s not like they were completely without religious texts.