Canto 3

Dante's inferno 

Canto 3

Dante does not officially enter hell till this canto, canto 3. He enters the outer region by passing through a gateway. Above the gate is the famous warning to "abandon all hope". The sinners in this canto are neutrals, people who failed to choose either good or evil in their lifetimes and so are condemned to exist in a place that is neither really Heaven nor Hell. It’s called Limo. Their punishment is various insects stinging their naked bodies, irritating them and making them run around in big circles under a long banner.Dante is blown away by the large number of neutrals being punished.

Personally I think this punishment is to harsh so the sin, actually I dont believe this should even be considered a sin because they did not deny God and they didn't choose evil either, they simply did not choose. I think neutralism should bot be a sin because I think everyone should have the right to freely choose(or not). Being stung by insects eternally is too harsh and does not even fit in with the sin(contrapasso).