" It (baptism) didn't save them, but it did add them to the church, as the Bible says."
IMO, I think this is where a difference of opinion exists...
Some people believe that when you are saved, you are automatically a member of the Lord's church and there is not a seperate ceremony or statement of faith or commitment or whatever. I'm not sure that any of us know the actual moment that happens as I believe salvation is a process. I believe it says in Acts that THOSE WHO WERE BEING SAVED WERE ADDED TO THE CHURCH. It doesn't say that they were voted on or asked to be members, but to me, implies that it was automatic. GOD added them. I hadn't heard Acts called a book of transition, but it gives the history of the early church, so I would think it would be considered valid whether it is applied to Jews or Greeks, etc.
Why would or how could one be saved and NOT a member of the church???
Also, IMO, the 'work' done in baptism is God's work, not a work done by a believer...it is something done in obedience to God's word. Besides faith without works is dead, but I think that's already been discussed here.
Whoever spoke for "mainline" churches of Christ is misinformed. There may be individual congregations that have some of the beliefs presented, but there is a lot of variation from congregation to congregation.
I believe we will be judged as individuals and not as congregations or denominations anyway and God will be fair and just.
It is our job to continue to study and grow. Many people change their opinions about issues over the years when they realize what they have been taught is a tradition rather than a command. It has happened to me and I'm sure God will show me more ways that I need to change in the future. Peace.