I am glad the NT is clear that you have to believe before baptism. There is no post-houmous baptism for the Christian.
actually, you don’t. They baptize everyone. But, belief after death is the key for it to “take”. That what you meant?
I used to live near a Mormon library and go there to do genealogical research. From the library you could hear the soundtrack from the visitors' center and I must have heard mention of that verse dozens of times.
It's the reason why they have an interest in genealogy--and they let non-Mormons use their facilities free of charge.
My take on it is that baptizing dead people by proxy doesn't do them any good and doesn't do them any harm, so why should non-Mormons worry about it?