'I wonder how a Christian would respond if an in-depth and historically correct debunking of Christianity was given?'
They fucking ignore you while plugging their ears with their fingers and singing 'LA LA LA LA' is a screechy, high pitched voice.
Start with Genesis and the firmament with stars attached to it. Explain to them that the very first story in this book is a complete lie. Then explain to them that the stars are light-years away from earth.
This will get their attention and they'll be all like, 'wtf?'.
Next explain to them that the firmament never held back water and proceed to rip their great flood story apart.
By the time you start asking them which of Noahs kids were harboring the AIDS and HERPES viruses, you'll get the screechy singing, ear finger pose.
Some people simply like being ignorant.