When Huck is spending time with the Grangerfords and learning about their violent, decades-long feud with the Shepherdsons, he joins them at church. His description of this experience contains situational irony:

Next Sunday we all went to church, about three mile, everybody a-horseback. The men took their guns along, so did Buck, and kept them between their knees or stood them handy against the wall. The Shepherdsons done the same. It was pretty ornery preaching—all about brotherly love, and such-like tiresomeness.

This situation is ironic because these two families—whom Huck has learned are out to kill each other—not only go to church together every Sunday but also bring their guns with them while listening to sermons on topics like brotherly love. The tension between what they claim to want (to destroy each other) and what their actions in this scene suggest that they want (to peacefully sit together as “brothers”) highlights the hypocrisy of religion.

While Twain is criticizing the hypocrisy of Christians who feel morally justified in enslaving Black people in the novel, he is also criticizing how Christians can be hypocritical in other aspects of their lives, such as the Grangerfords and Shepherdsons carrying out a violent feud six days of the week and acting peaceful and "brotherly" on Sundays.