Spirits are supernatural beings that exist above and beyond the natural laws of the Universe (though when acting within the Universe, they are bound by its natural laws). There is little that can be said of their intrinsic nature, though it is known that they have no inherent physical form, and can appear in whatever form they choose (generally taking on the form of whatever intelligent species may live on a planet they visit, such as humans, elves, or merfolk on The Land). Whether or not they can die is also unknown, though it is assumed that short of being killed by another spirit, they would be immortal. Unlike most of the Universe's sentient races, it is believed that spirits cannot reproduce among themselves, though God can create new spirits, Himself, at any time.
The chief of all spirits is called simply God, though He has gone by many names on many worlds. (It should be noted that "God" is actually a title, rather than a name; His true name is unknown, though it is known that He gets angry if anyone else uses the title of "god" for themselves, or if anyone bestows that title upon anyone other than Him.) He created the Universe and all life within it, including the other spirits (the first generation of which He created prior to the creation of the Universe). Though God alone among spirits is said to be omnipotent, omniscient, omnipresent, and omnibenevolent. (Part of his omnipresence may be attributed to the fact that He can split Himself up infinitely; such is the case with a part of Him known as the Holy Spirit. On Earth, the Holy Spirit is said to be one of three parts of God, though itself it is apparently divided into many parts. On the Land, God only has two of the three parts that are known on Earth. The Holy Spirit is somewhat different here, as it automatically surrounds and protects all Landian souls, whereas on Earth it does so only with those who have been "saved" by virtue of the third part of God, which never came to the Land.) It should also be noted that, while it is common for Landians to refer to God as a spirit, this is technically erroneous. All spirits were created by Him; He was not created by anyone or anything, but simply always existed, and does not belong to any classification of beings. The reason Landians tend to think of Him as a spirit is that He appears to behave in much the same way as spirits, when conversing with spirit-talkers. However, His powers go far beyond those of spirits; He is the only being in the Universe not bound by the natural laws He created to govern the Universe.
There is another spirit, called Lucifer, who has, like God, gone by many names on many worlds. Apparently at some point before the creation of the Universe, he rebelled against God, and various spirits joined his side in a civil war. God, Lucifer, and all spirits lived in a dimension called Heaven, but God created a new dimension called Hell, into which to cast Lucifer and those spirits who had fought on his side, when they lost the war. Heaven, it is said, is a place of pure perfection and bliss, whereas Hell is a place of absolute misery and torment. It has been suggested that after people from any of the worlds in the Universe die, their souls may be transported to either Heaven or Hell, though the determing factor of this is, apparently, different on every world, depending upon the course that religion has taken on each world. On the Land, it is said that those who have predominantly evil hearts go to Hell, whereas those with predominantly good hearts go to Heaven. The criteria for what is "good" and "evil" are judged by God Himself, though there are those who debate whether His opinion is truly more valid than that of the people He's judging. In any event, it is rare for Landians to give the "afterlife" much thought; most simply try to live their lives the best they know how, and leave it at that.
It must also be noted that there has been an ongoing "cold war" between God and Lucifer ever since the end of the civil war in Heaven. Though defeated, Lucifer has never given up hope, apparently, and the Universe has provided a new stage for their rivalry. Each attempts to influence the hearts and minds of the people who inhabit the worlds created by God, though to what end is unclear. However, God visited the Land often, in the decades after creating this world and its first two people, Connor and Brigid. But upon their deaths in LY 52, God ceased visiting the Land for quite some time, nor did any other spirits visit Landians. That is, until the year 100, when Lucifer appeared to a farmer named Brist, and encouraged him to spread the concept of religion among the people of the Land. (This is the Land's Fall.) Lucifer claimed that both he and God had mellowed over the millennia, and their war wasn't now as intense as it once had been. Ever since then, other spirits have visited the Land much more frequently, and those who speak with them regularly are called spirit-talkers. This interaction has greatly increased the pace of Landian development in innumerable ways, though perhaps most notable is their assistance in introducing magic to the Land. (It's also quite common for spirits to share knowledge about other worlds, most popularly Earth.)
Over the centuries, spirit-talkers have seldom bothered to differentiate between spirits who follow God and those who follow Lucifer. However, it should be noted that on the rare occasions when such distinctions are made, those who follow God are referred to as "angels" and those who follow Lucifer are referred to as "demons." It isn't known how Lucifer or any of his demons are able to escape Hell to interact with people in the physical Universe, though upon the introduction of vampyres to Landian society, it was learned that there are certain limits to what demons can do in this dimension, except under specific circumstances, which involve revoking the Holy Spirit's protection of individual souls.