I'm well aware of the verses...
You admit then that there are no 'unsaved' in the church...At the same time there can not be any that do not know if they are saved, since only the saved already are members of the church...
If you must endure to the end, you are not saved til the end and you won't know til the end if you are really saved...In which case, that person can't be a member of the body, the church...
We are saved by the grace of God and made members of His Church. But we must cooperate with that grace and perservere. Why do you think that Jesus said that not everyone who says Lord, Lord will be saved, but only those who do His will? Read St. Paul - he talks about it all the time - "fighting the good fight, finishing the course." You know, I don't think you know your Bible as well as you think you do.