"The blood shall be a sign for you on the houses where you live; and when I see the blood I will pass over you, and no plague will befall you to destroy you when I strike the land..."
In addition to the normal Statistics that describe how strong, fast, durable, and so forth a character is, there is also a set of statistics, known as Resistances that show how likely a player is to withstand certain magical effects thrown at them.
In the early stages of the game, there were plans for Resistances to be based on the eight Winds of Magic, although this is no longer the case in current builds of the game (presumably eight resists was seen as too many). There may also have been a resistance named Lumina which is not currently in the game. At the moment, there are three resistances which correspond to different damage types you can find in spells and special attacks:
Spirit - which represents your ability to resist spiritual attacks, such as various holy magics.