This is an extract from a letter written 18 August 1994.
You mentioned the way in which the translation of ekklesia or 'ekklesia' has changed from 'congregation' to 'church'. That is only part of the story... the subject seems like a fairly major one to me. After all, when Jesus talked about building His ekklesia, what did He - and His hearers - have in mind?
The word 'congregation' has the connotation of a fairly responsible, respectful and subdued group of people. Perhaps 'assembly' would be better, but that still sounds essentially ordered and controlled, like a school assembly. The original refers to any assembly or group of people, and is about as unspecific as you can get. When the Ephesian riot was in confusion (Acts 19:32), the mob is called an 'ekklesia'. Some church!
The etymology might derive from 'called out', but only in the sense that the rioters in Los Angeles were driven out of their homes by their anger against the court verdict. There is nothing formal, legal, or divine about the calling - people are called out by their own choice to participate in whatever is happening.
Clearly, whatever Jesus had in mind, His hearers would never have guessed He was referring to anything like our normal church service, a charismatic or Pentecostal service, or any sort of formal gathering. When He said 'My ekklesia', it was to distinguish His people from all the other groups in the world.
Not only is there no evidence He set out to found a religion, there is no evidence He set out to found an organisation. His people were to be something like a family, and something like a nation, but then both those words have changed somewhat in meaning over the years, too...
The problem is very similar to the one we have with the word 'baptism', which to us is solely used in connection with Christian initiation rites. The original simply meant to dip, plunge or immerse, and you could baptise a brick without anyone turning a hair, if you really wanted to. You would baptise your clothes when washing them.
Of course, the word was also used in a religious or ritual context, but most of the arguments we have about baptism these days would have been quite incomprehensible to Paul and the other apostles. Of course you can be baptised more than once - if Baden-Powell had been alive in those days, you would have been baptised into the Boy Scouts. The only difference about Christian baptism is that your were baptised into Christ, as opposed to the Boy Scouts or whatever other social group you wanted to join. Baptism as such was of little interest to the early church - only the 'into Christ' bit mattered.
Please forgive me - I get excited about such things...