There are hundreds of Old Settler religions. They vary from high-minded mono- and pantheisms down to base superstition, and show remnants of many other religions, most now extinct in Imperial Space. Their exile to the outbacks of their worlds has been hard on their high-mindedness, though.
Common objects of worship among the less enlightened Old Settlers are: ancestors, the Old Terraformers, "Yarth" (Earth, the homeworld, from Schmidt), and the usual assortment of departmental deities.
In Schmidt's universe, a well-known Old Settler god is Patham, a war-god and a judge of the dead, who has a selection of seven hells to send his enemies to. Swearing by Patham or his seven hells or the seventh one is a popular frivolous exclamation, similar to "By the dog!" among Greeks of late antiquity (referring to the Egyptian god Anubis).