I have been to one such funeral. The minister painted such a saintly halo for the guy that I ran outside, to check the address to make sure I was at the right funeral. I laughed all the way home. He was trying to fool St. Peter or someone.
The guy's kids were probably there, and while it is easy to laugh at something like this when it didn't happen to you, such a heartless assault on the memory of a loved one while grieving is despicable. Can you imagine what the kids at the funeral were thinking? Telling his grieving kids that he was in hell?
Even if we haven't a whit of compassion for the mourners, this behavior is in such apallingly bad taste as to boggle the mind.
I would sue for intentional infliction of emotional distress, as well as breach of agreement and/or fraud.
If the deceased is indeed in hell, we can be sure that he will be afflicted with the company of this "preacher" in due time.