More about the Southern Catholics...er, Baptists I mean
However, the Great Commission commands us to go out into the world and the four corners of the earth. Thus, I believe that we are supposed to be in the world.
Jesus walked amongst those that society rejected. He sought out those with fragile faith and sought to challenge them and instruct them. He didn't hang out with his disciples all the time, nor did he hang out with the Pharisees discussing matters of theology. He walked, talked, and lived out his faith.
With all of that, I get a sense that by calling Southern Baptists to pull their children out of public schools, Pope Al Mohler and the like are seeking to build up walls and are moving away from being "in" the world.
Teachers and students that are Christian, and more specifically Baptist, do not need to be cloistered behind the walls of a private school. They are what public education system needs. What better way to demonstrate the love of Jesus and what it means to follow him than by daily taking up his cross amongst your peers?
I believe the same idea lies behind how our churches are supposed to interact with society. Just as so many Christians believe the government should not be in charge of social programs, why do so many believe that the government should establish the morality of our society? The church needs re-examine its role.
When the church building is empty, it's just a building. The church consists of people - if the building burns, the church goes on. Us Christians must actively engage society through the institution that God gave us, rather than that of James Madison.