One common challenge to the idea of Christianity in general is the
idea that many people are only Christian because they were born in a
predominantly Christian society. This argument takes many forms. One
common claim is that if the same person (who claims to be Christian)
were born in Iraq, they would be a Muslim.
Other times, the claim might be more along the lines of the idea
that someone is a Christian because their parents raised them that way.
In other cases, they may attribute someone's faith to a reaction of some
tragedy or trauma in their life.