Quatermass

I had a series of discussions with a Calvinist regarding legends in the bible. He readily admitted that the early chapters of Genesis were based on myths and legends but went on to say that once you got to Abraham, the book shifted to a historical perspective. Considering that the Abraham narratives include kings lusting after 90 year old women, God walking around in the desert, cities being destroyed by heaven-fire, fathers of nations being conceived via single night drunken incestual encounters, etc., I find it a stretch to call these stories historical.

Having left the fold, I find it incredible to NOT see stories all through the bible as legendary in nature. How does a Christian dismiss stories in non-biblical literature as unhistorical (not based on fact) while accepting biblical stories as historical on that basis alone?

emotional

It's very much conditioning and autosuggestion. Your average Christian (and Jew, and Muslim with regard to the Qur'an) will be either accustomed to hearing the Bible read from an early age and thus rendered musical to him, or simply seduced by the language and imagery. Starting on Genesis 1, "In the beginning [when] God created", there's a magical sort of lure to it. Non-Biblical myths usually tell of many gods, which most of us are conditioned to disbelieve, whereas the Bible tells of one god, which sounds credible (though I've long lost any credence in the one single idol of monotheism...). I don't believe the Bible is literally true or even has theological authority, but I admit the language and rhythm and imagery of the Bible are very seductive. It must be a matter of culture, because Muslims say the same about the Qur'an while at the same time dismissing the Bible as worthless trash.

BTW, not all the Bible is mythological, some is definitely historical, eg the siege of Sennacherib on Jerusalem is documented in Assyrian tablets too (the name of King Hezekiah appears on them: HAZAKIYA YAUDAA in cuneiform, meaning "Hezekiah of Judah"), so it certainly happened.