Divided Down the Line

So in today's "emerging church" (what are they emerging from anyway?) the concept is megachurch with multiple campuses (I guess this is how Paul did it? He was the spearhead of the whole movement, or would that be Peter, since he was the rock that the church was built upon?) Before there was consumer transportation, people didn't visit other churches, they either went or they didn't.(in the early 17 & 1800's). There was only one church in your region and this church was generally a denomination that the majority of residents in the area were associated with. This church was lead by someone with or without any theological learning, typically the person with the best grasp on theological matters was the one who led the congregation. Then someone with theological knowledge would travel the circut and preach about once a month.  


Then we have today, where in Garland County alone there are over 142 something churches of at least 15 denominations (probably more) to choose from. You could easily drive to any of these within enough time to get to service on Sunday morning. Why do we have so many churches? Sure there are things in the Bible that people don't agree on, as well as rituals that people think should or should not be in place, but why not just agree to disagree? I realize that orginally Protestant's reformed from the Catholic church and thus the church is constantly evolving in order to stay in line with the scriptures and not get bogged down in ritual but surely we could all agree.  


The thing is, there wasn't two churches in Phillipi or Ephesus just one, and the only reason during the early days of our country (1800's moreso) that there was more than one church, was to reach the different cultures. So why then, can't we all agree on one general group and thus be more effective for the Kingdom? I realize that Paul talked about differences in culture, but did he ever talk about different denominations among believers? I don't believe so, at least I've never heard that preached on before in church. So then should not our churches be divided along cultural lines, and not on whether or not a person is a Calvinist.