RR,
My first year at the convention was completely different from what you describe. Erick Grieshaber gave a very special talk about Jesus, what He had done for us etc. I would have never thought I would go to the alter in front of several hundred people and say "the sinners prayer" giving my life to Jesus, but I did.
I have gone every year since, this will be my 10th year. Joan would never consider letting a non-believer direct worship or anything like that. I can't imagine why you had that experience, but, I can assure you it is not that way now.
Most of the talks are spiritual, of course there are always comments about our former lives in the WT, what the latest WT happenings are, etc, but, I would say about 90 % of the program is Christ/spiritually oriented.
You should give it another try.
Borgfree