Given that the world contains 6,890,215,699 people
Source as of Dec 29, 2010. Of these people only about a third or roughly 2,100,000,000 profess to be Christians
Source as of 2005. In the United States as of 2010 about 76.5% of this countries population profess to be Christian
Source as of 2001. When viewed from a larger perspective this means only about 11.3% of the US makes up the world wide Christian community
Based on the the US population estimation of Dec 29, 2010. This 11.3% gets drastically smaller when we start focusing on individual states and drops to insignificant numbers when we start looking at cities and towns.
The conclusion: When someone makes a generalization about Christians based on "all the Christians they know" you have to wonder, how many people do they actually know who profess to be Christians to make such an assertion?