The Heltras were a British 'brotherhood' of humans and aliens who loved war and conquest and wanted the 'Chosen One' to become their greatest weapon. They believed that if they command the entire universe, they will be invincible and have all power until the end of the universe.
The Heltras thought that freedom and peace were what bound life, as they needed to be maintained. Chaos and fear mixed with an eternal war and conquering all things gave purpose to them and purpose was what lifeforms strived for. Because chaos was random and needed no true effort to keep, the Heltras found this to be the perfect thing to keep and that through war, chaos could remain and when they control the universe - their purpose then would be to keep control.
The Child's role
The Child's powers were seen as the ultimate weapon and could give them enough power to easily conquer and 'convert' planets. It was thought that the Heltras would be the ones to make the Gorndals' prophecy a reality, but as they were all killed trying to find the boy, it is not possible.