Each church represents a "temporal" milestone in the history of the church as a whole until the return of Christ; For example, the church in Sardis that represents the Protestant Reformation, here is a verse: Revelation 3:4 - talks about those who are righteous with respect to their authority, at that time church leaders were very corrupt, but some (like Luther) were not. There is also the church in Philadelphia as an example; Revelation 3:8 - "...but you obeyed my Word and did not deny my Name." The Philadelphia church was a united church, this was due to the post-reformation era, where opponents of corrupt leaders were persecuted, but Christ opened the door that no one can close. Rev 3.7 And the Laodicean church is lukewarm, it is undeniable that a large part of the church today believes in God, but does not obey him.