According to James Barr, R.H. Lightfoot once claimed that the origin of the New Testament should be sought in the moment the early Christians, under the impression of the ﬁrst Roman persecutions, lost faith in the survival of their religion. As a result of their fear, they decided to write down their traditions and recollections, in order that these might not be lost or deliberately perverted. (Cited by NP Lemche in his essay ‘The Old Testament: A Hellenistic Book).
Lightfoot is probably right. And if so, it’s a good thing that they were driven by the fear of extinction. History has shown their fear to be misplaced but the result of that fear is itself a historical monument without which the world would be an utterly different place.