Why does Twain suggest that having the king and the duke pull their first "con" at a religious revival? (This might've been asked. If so, it's desperate. If not Okay!)

"Twain suggests that there is an undercurrent of nastiness to these two characters. They perform their con-job in a sacred place of worship. Although Huck doesn't care much for organized religion, he recognizes the symbolism of what they are doing."