I guess I just don't get it.
Yes, the first century christians got things wrong.
No, the first century christians did not disfellowship someone for not agreeing with something they got wrong.
Am I right in that understanding??
I can think of a couple things that some individuals in the first century got wrong:
-circumcision
-eating idol meat
-john's death
Jehovah's Witnesses get things wrong.
Jehovah's Witnesses do disfellowship someone who doesn't agree with current teaching.
How is that similar to the first century?
If the WTS writes that the end is coming in 1925; then that's it - the end is coming in 1925. When it doesn't come in 1925 new information will be presented to show why and a new date if available will be provided. All will adhere to the current information under pain of everlasting cutting off.
That makes them odious not dubious
Especially when the organization directs that your immediate relatives cut off association with you.