The Chanters are a cult with roots far back in pre-Exodus Terra. Chanters believe that by endlessly repeating certain phrases, called mantras, they can improve their luck and bring themselves various rewards of their own choosing. 
The chanting cult is more or less tolerated by Kuritan authorities, mainly because it is so focused on the desires of each individual that there is little chance of it taking interest in any larger social issues.  
Indeed, chanting for luck is popular in the military, especially during combat. It is also true though that Kuritan commanders have had problems with Chanters using open mikes to jam tactical communications. This behavior ended with Mantras using numbers to be outlawed in the DCMS military because they are too often confused with artillery fire coordinates. 
- House Kurita (The Draconis Combine), p. 119 "Pillar of Ivory - The Mysticism of Five - Off-Brand Sects"
- Handbook: House Kurita, p. 111 "Pillar of Ivory (Culture and History) - Minority Religons - Off-Brand Sects"