Christianity merged with Rome, in the 4th century AD, to form the Roman Catholic Church. This is when Christianity became more formally organized and structured. The new Roman Church became an integrating tool for a world superpower.
Before that key merger, there were seven main Christian churches, with each having its own personality. The church at Philadelphia, which was a city located at an important trade crossroads, in what would be modern Turkey, was the most optimized of the seven Churches. It is not coincidence that the founding fathers of the USA would write the Constitution, in a city with that same name; city of brotherly love. They were well aware of the symbolism.
The original idea of having many churches was connected to the promise of the spirit. The promise of leaving behind a living spirit, by Jesus, implied an organic approach to faith. Religion was supposed to be like life, which grows and evolves. Life also forms distinctions which nevertheless integrate via ecosystems. One does not need a living spirit, if the goal is to carve, one way for all, into stone.
Gnosticism attempted to retain the living spirit of inspiration and change, trying not to reduce God and religion to some linear bureaucracy. The Church at Philadelphia was an example of living faith in action. The members of the Church were able to apply their faith, in new and changing situations. They lived in a place where people of all races, faiths and lack of faith, merged for commerce, along the trade route.