One of the first things that I have to teach my students this: The Christian faith is not a house of cards.
Most assuredly, there are foundational issues of the faith that, if taken away, will destroy Christianity. Issues like the existence of God (there is no such thing as a “Christian atheist”), the resurrection of Christ, the reality of God’s judgment and grace through Jesus Christ, and Christ’s atoning death on the cross. However, there are many details of the Christian faith that can suffer adjustments without destroying the entire faith. Christianity is not like a house of cards where you can take any one card away and the rest fall.
I have seen many people leave the faith and the catalyst of their departure was a rejection of inerrancy (the belief that the Bible does not have any errors, historic, theological, or scientific). I have seen others leave because they felt they had to adjust their view of the early chapters of Genesis, creation and the flood. I have seen others who thought that if there was any redacting (editing by the authors) of the Gospel narratives, their faith was destroyed. Still, I have actually been in contact with one who was shaken to the point of petrification because he was starting to consider the multiple author theory for Isaiah. These are issues to be sure. But they are not issues which can cause any harm to the essence of Christianity in any way.
It is normally those who are brought up in rigidity who are susceptible building this house of cards theology and to letting non-cardinal issues crash their faith. This is why you see so many who are “former fundamentalists.” Fundamentalism feeds on unnecessary rigidity and therefore, unfortunately, is quite a seedbed for graveyards of Christians. As well, this type of thinking makes education—true education—virtually impossible.
While I believe strongly in many issues that are of non-cardinal value, I don’t hold on to these too tightly. This is a fundamental philosophical precursor to dealing with so many theological problems today. The inability to identify, isolate, and distinguish between essentials and non-essentials often causes the entire house of cards to fall.