Bar Mitzva Speech
There is a clever commentary by the Chidushei Harim, that explains the justification of Shimon and Levi to kill all of the males in the city of Shechem.
He claimed that both boys were thirteen years old at that time. It was already a custom for the Bar Mitzva boy to give an original Dvar Torah, in celebration of his milestone.
There is a Halacha that states that if a Noachide observes Shabbat, he is deserving of the death penalty. For this reason, conversion candidates do one Shabbat transgression until their conversion is complete.
They reasoned that just as one who observes Shabbat is put to death, as Shabbat is referred to as an אות, “a sign,”the same would apply to Gentiles who perform circumcision. Brit Mila is referred to as an אות, “a sign” on the flesh of every Jewish baby boy. This was their Bar Mitzva speech according to the Chidushei Harim.
There were other reasons given as to why the whole city was put to death. They were not allowed to condone rape, and they were obliged to set up courts of justice. This made them all complicit in the terrible violation of Dina.
On Yakov’s death bed he cursed the anger of Shimon and Levi. He did not curse them for the act they did. Maybe the Bar Mitzva boys were not that far off the mark, in their Dvar Torah on their great day!