But a "believer" doesn't NEED all the Xs and Os. A believer only needs "the word" and his or her faith. No explanation consonant with natural law is necessary - "God did it." To a non-believer, the explanations are similarly unnecessary, since the non-believer is quite likely to recognize a mythic theme that crosses many culture and mythic systems (virgin birth), and the christian implementation of it is simply evidence of the fact that christianity & its scriptural artifacts are indeed part of "the big picture."