In the third chapter of Hilkhot Teshuba, Halakha 5, Maimonides asserts that the Jews and the righteous among the gentiles (chaside ummot ha'olam) will have a share in the world to come ('olam habba, i.e., the afterlife).
Then Maimonides writes about the exceptional cases. Those who because of the severity of their sin would be excluded from the world to come, unless they repent during their lifetime. Maimonides enumerates twenty four categories of sins, some of them related to radical statements or ideas like, denying the existence of God, or His unity or His incorporeality, etc. and some of them related to severe sins, mainly in terms of their irreparable effects, like treason (moredim, moserim) killing, slandering (ba'ale lashon hara) etc.
Interestingly, toward the end of the chapter (3:14) Maimonides refers to eight cases, seemingly of a lesser severity, which were also mentioned (strategically) by the Rabbis among those sins for which one losses his or her part in the world to come.
Four of these cases could be translated in modern term as "bullying" (nicknaming, verbal offense, embarrassing someone in public). Bullying is a kind of verbal abuse which's effects are not less severe than physical violence. Unlike physical violence, bullying is not penalized by the law and it could go unseen for a long time. It is uncommon for the victims of bullying, especially in cases of low self esteem, to denounce the perpetrators, and the torment might go on with devastating emotional effects. In our days bullying is unfortunately epidemic. In some cases the class (or the bus) is divided into three groups: the bullies, the victim/s and those who watch (=bystanders).
As parents, we need to be alert and detect the symptoms of bullying. We should educate our children to denounce bullying and, as importantly, we should teach them to respect, and when necessary defend the dignity of every human being.
