Religions

Gods exist in this universe and were created thanks to the power of "faith" by the people living in the universe, not the opposite. The "main" one is a mix of all the leading gods in the diverse religions, giving him quite an ego. Scandinavian, Egyptian, and others are also part of the pantheon, but polytheistic religions gods tend to have less power than a monogamist, as their faith and powers attributed are both separated into smaller pieces. Fictional gods exist as well. For instance,

- Elves worship Gaïa, goddess that represents the planet itself. 

- Dwarves worship Erskïne Bardonyx, a legendary leader who gained the trust and the faith of the entire race when he used his leadership to unite all the clans into one brotherhood, he collected enough faith to ascend to lesser god levels of power and stopped from aging

- Orcs worship the spirits of their fallen comrades and their totem animals, they give them a small boost of strength in situations of need

- The humans of the desert branch worship gods similar to those of the Egypt mythology

- They are some minor cults too, for example, some people are still worshipping the spaghetti monster, but their lack of serious members and that one guy that keeps eating the plate keeps them from making anything threatening. A few weak crab-like monsters have managed to spawn and reproduce, however, but they are not strong enough to seriously arm a humanoïd. 

Some elements have the power of boosting the efficiency of prayers, and gods made sure mortals would find them extremely valuable. Gold and gems are one of those materials but must be shaped into an altar before having any noticeable effects (you can't just pray to your coins.). Souls can provide faith, but at a much smaller scale (like maybe a quarter, maybe less) and cannot be boosted with an altar. Lucifer uses the immense amount of souls of hell to compensate for the fact that not many living people worship him on Gaïa.

Hell and Heaven

When you die, you can go to either hell, purgatory or heaven.

If you are a nice person who did nothing wrong and lived a neutral life, you will go to hell. Don't worry! Hell is actually a nice place, just pretty crowded. Hell cities actually look a lot like cites of japans, have way too many people for the amount of space they have. The place is lit with various colourful gemstones. Souls cannot use mana tough, so no magic here. It is "famous" for its various hot baths or "osen" (probably wrongly spelled sorry) due to the fact that it is located closer to the center of the earth. Hell work on a system of one day you work to accommodate the "unlife" of someone, the other day they might be the one working for you. People that live there are recognizable for being made of flames, rock or magma. Why? Let's ask the big guy himself:
Lucifer, satan, or the big boss, depends on my mood - Satan:
 "Takes quite a lot of power to grant someone a fresh new body, and you can't just let people make more life when they are dead can ya? Instead, I try to use something cheap but of nice quality, something I can easily find around here, you know?" 

Purgatory looks more like the hell people fear, with flames, pain and all. it works on a system of guilt. If you regret your sins and deeply wish to be forgiven, you will be forgiven. Of course, your guilt must be equal to the crime you have committed, so you can't be a little sorry for having murdered a child, you must deeply hate yourself and your actions and be ready to prove to the one you wronged how strong your convictions are. Sadly, some people only learn with physical or emotional pain, and nobody that is nice and doesn't deserve punishment would want to torture someone else, and if they do, it would defeat the purpose. This is why Lucifer had to create Demons. Demons are naturally evil creatures that are physically unable to feel remorse and feel pleasure on making others suffer. Those magically powerful creatures (as they often have to create illusions or deal important burning pains.) are craved by people of the surface searching for easy power. But making one escape purgatory is no easy task, and they are pretty much never reliable. Souls do not have the handicaps or their physical form, so someone who was unable to feel emotions when they were alive can be horrified by their own actions and can more easily be forgiven, but it is still not an easy pass either.

Those who go to heaven are only a select group, who are mostly composed of priests, kings and such. God personally chooses those who provided the most faith towards him and decide to reward them personally. Those people are not sin-free, quite the opposite, they are often sinners who managed to buy their place in heaven. Some of them sacrificed their whole life to worship him. His favourites are chosen to join his angel army, next to his 4 arch-angel generals. God uses his power to grant the wishes of the people who live in heaven. 

Lucifer: " Those angels, creatures of God. They are beings enveloped in flesh, just like the living, so they can feel the pleasure of the touch. But they got something different inside. Since he got way fewer people to deal with and got way more faith to spare, he can afford higher quality bodies for his "chosen's". "

Technology

Readers might have realized that something was off with technology. Foldable tents? I tough this was medieval times! Well, not entirely. The story actually takes place in modern times, but in a medieval-ish period that has been stretched with the wonders of magic. No electronics exist, as the taming of electricity has not been invented yet (apart from destructive lightning-like spells). While you can see furnaces, dishwashers, and other convenient machines, they are instead powered by mana batteries and runes to control their functions. Their tasks are usually straightforward, so you cannot control the cooking time of a furnace, for instances (but you can control the power of the spell, or stop the casting) and you must check periodically in your dishwasher to see if the dishes are cleaned yet. It will only spray pure water (plus "soap"). Elves focus more on magical plants that have similar properties grown to have the desired effect. They do so with the help of their lesser god the goddess of nature.