The Bible does say the wheat (true Christians) and weeds(false Chrisitans) grow up together until Christ comes with his Angels to sort them out.
Glad you brought that up. I was going to talk about this as well, but just didn't get to it.
Don't worry about that 'invisible church' thing ;) The main reason I brought it up is because I myself used it for quite some time, but eventually started looking at it from a differant perspective. I realized that I was actually using the idea of an invisible church to actually write off every group out there as not worthy of consideration. (I'm not saying you do this) So I personally like to be balanced when talking about true Christians being scattered. The main purpose is to insure that no particuliar group takes for itself the role assigned to Christ, that of being the agent of our salvation. When any group does this (JWs and all the others) they violate scripture and the main message of what it is to be Christian.
Also, don't give me the credit for 'organism not organization', I picked that up from Barnhouse and I'm sure he got it from somebody before him. It's a great way to look at it though, isn't it?