Let's imagine a true melting pot of a church. A little bit of everything from every dividing line we can imagine. The only way to connect with that many different types of people is to be neutral. (That is not to say shades of grey or no absolutes). Obama's campaign was successful, in part, because he made a lot of general statements that anyone can connect with. He had principles and sticking points, but they were surrounded by vague generalities.

Rap music is culturally exclusive (not racially or socioeconomic, but culturally). The minute you introduce rap music for more than just a rare "special", you will divide along a cultural line. (This is not necessarily a bad thing, btw). There are some who will LOVE what you are doing, some who will tolerate what you are doing, and many who will leave. (again, not a bad thing).

The only way, I think, to be the melting pot is to be in the middle and avoid the extremes. A pop music pop culture church will reach across many cultures, will reach across socioeconomic boundaries, political boundaries. It will introduce the gospel to a large majority of our society. But it will miss the fringe.

Rap, skaters, heavy metal, artists, etc… these fringe groups will not be evangelized or served by a melting pot majority.

Of course I still don't have the right question, let alone the right answer. I think part of the answer lies in unity and cooperation with other "churches" as The Church that Christ intended. At that point we are not only a melting pot, but we are dynamic at the fringes as well.