Right from the start you will be able to build an altar to your god (provided you've not chosen Crom), and from the given altar you can craft your religious Artifact and get access to some helpful Recipes. You gain favor for the three gods in different ways. One such option is by killing other players or human NPCs and using your religious artifact on their dead bodies.
- Use your Setite ritual knife to cut out the hearts of your enemies and bring them to his altar to gain Set's favor.
- Gain Yog's favor by using your cleaver to harvest unblemished human flesh and roasting it in a Yog pit.
- Purify the bodies of fallen enemies with your Mitraen Ankh and bring the lingering essence of their souls to an altar of Mitra to gain his favor.
- Gain Ymir's favour by using your Hoar-Frost Hatchet to collect ice shards from cutting down trees.
Altars are paramount in end-game defense and offense. Neglecting the power of the gods invites another believing clan to absolutely crush your structures using Avatars. You can use an altar to defend against enemy avatars through religious forcefields.
The altar of each god has three tiers, and you need to gather a lot of favor to be able to upgrade them. You also need to progress through the ranks of the clergy in order to gain access to the different tiers of altars. Each tier unlocks additional Recipes, such as strong religious Weapons or particularly nourishing Food. But getting to the higher tier or altars requires effort and you must have gained much favor with your god. It is therefore advisable to join up with other players and form a clan, so everyone can work together to gather favor. If you have the highest tier of altar and an arch priest, you will eventually be able to summon your god’s avatar to smash your enemies.  Also worth noting is that not every member of a clan needs to have spent knowledge points learning the religious recipes since just one player can craft the religious implements and Items for everyone in the clan.