Was New Testament Material On Jesus' Childhood Based Only On Oral Tradition?

Critics often say or imply that the early Christians were more dependent on the oral transmission of information than they actually were. This past Easter season, I wrote a post about non-extant documents on Jesus' resurrection, including documents that predate the ones we have. Much of what I wrote there is applicable to Christmas issues as well.

We shouldn't think that information on Jesus' childhood was passed on only orally prior to the writing of the New Testament documents. In fact, the idea that nothing was written about his childhood prior to the time of the New Testament is antecedently improbable, so that those who hold that position bear the burden of proof.