I'm a supporter of freedom of speech, so whatever they want to preach they can preach. However, I have to say there is a difference between saying your opinions in your church, and going to a funeral and trying to spread your hate to a mourning family.
And if they really want to spread a message, why not try and convert the living, instead of just saying dead people are in hell? Then again, I guess in some regards it's good that they act the way they do, as it means people are far less likely to be drawn into the church, so they will always remain a minority.
By the way, has anyone seen Louis Theroux's documentary "The most hated family in America"? It's where he goes and lives with the church for a short while to learn about them. It really made me feel sorry for the younger generation in the church.