Given that my career is teaching and I have been specialised in Religious Studies for the last 12 years, I suppose it’s no surprise that I highly value religious beliefs and practices in my roleplaying game worlds.
I know it’s not fashionable in this secular age but there is a lot of interesting stuff you can do with religious people, places, and things. The main barrier to this is the interest (or lack thereof) of the players: if no one else is interested, the wonderful richness of the religious orders in your world could easily lie fallow.
In the past, the default for me has been to see if anyone picks a religious character before deciding to invest in religious organisations. Because I start with a skeletal outline of the world for players and then move quickly to their character role-up, I can be flexible about the degree of religious detail in my world.

In Mystamyr there originally wasn’t much interest in Clerics so I ended up creating the Temple of Ten Thousand, inspired by an obscure text written by David Hargrave for Arduin. This model seems to suit modern secular players because it’s inclusive and treats all faiths equally. Going to one temple filled with thousands of shrines is a rich environment to explore but also a simple approach to religious practice.
For the longest time I have wanted to create a rich pantheistic religious tapestry for players to explore but sensed that the interest would be limited.
Of course, the brave thing would be to work out the pantheon and introduce it to the game slowly. Little tidbits of information, small clues, and characters who are involved in the complex spiritual reality of the world would provide a good way in for curious players. Those who want to play priestly characters can pick a deity and be given a particular worldview from which to begin. It’d be fun to allow them to run into the realities and counter-worldviews through play.
Another option, given my own faith, is to present the older forms of the Christian tradition and allow players to explore this worldview through play too. Orthodoxy has a rich lore and the deeply symbolic nature of the religious practice would be evocative… providing players are happy to play with real-world religious traditions. The Northern Isles began with this as a default but I have been a little uncomfortable because it has made the game feel more historical than mythic. But you learn from your mistakes.
The main concern for me is to treat religious people, places, and things with the respect and seriousness that merits their invocation. Treating religious organisations as healing parlours and priests as healing drones robs the game of many possibilities. Temples cry out for factions. Priests can be moral or corrupt. Beliefs allow you to play around with morality and horror as intriguing themes.
Nowadays I have found that the best way to invoke religious themes is to build them in, right into the fabric of the world, and have them active whether players choose to play priests or not. Starting slow with clues and hints, you can tease the players with interesting adventure hooks and see what they fancy exploring. All the time, whether in the foreground or background, the Gods of your world will be active.
When the reality of the game world is actively filled with deities, all with their own agendas and desires, the players will be hard pressed to maintain a secular distance. They will be targets of persuasion, tools for factions to recruit, and powerful allies or enemies of these celestial and diabolic powers. The first time they decide to seek out a healer, make sure there’s a hefty price – not of gold, but of favours. From there, draw them into a web of intrigue and see what kind of a mess they can make.
Game on!