The Kingdom of Neshaten follow a goddess called Chi'lerious, their religion is considered monotheistic and they believe that their very people were created for some grand higher purpose, but they don't know what that purpose is or when it'll materialize.
Their religion is called Kurieste or, 'Honoured Soul', and they believe that as long as they remain true to themselves and don't harm those who can't be harmed, that they'll obtain this higher path. They do believe in an after life, brought on by strange occurrence in the past of people having deja-vu in relation to areas that person has never been to, but that people in the past have.
Because of their beliefs, most of the people do in fact believe in Chi'lerious. There are small groups that don't, but because most of their society isn't governed by their religion, it isn't an issue if someone doesn't believe in it. Only certain areas of their culture are actually run by the religious, such as the Rite of Honour.
It wasn't always that the Neshaten were mostly united under one religion, however, during the The Great War (Neshaten) that nearly lead to their extinction, many began to question whether their god actually existed - due to their goddess never materializing to help or even fend off those who were causing harm to those who were very devote. This changed when the Neshaten evacuated a large portion of their population to evacuation transports and sent them off into space to find a new home, although all but three of the transports were lost, those who were still religious believed it was a sign.
This sign stuck together and after the Neshaten resettled, their religion boomed once again. Although there are pockets of people who don't believe, those who think that the goddess doesn't exist, the Kingdom doesn't mind these non-believers. As long as the non-believers don't interfere with the normal running of the churches and the festivities that come with it, they are left to their own devices.
Non-believers don't have a name to them, and even those who are devote don't either. A person's belief in Chi'lerious is only used when joining certain professions, such as Swordsmaster in the military, or the Order of Marius.