There are no Gods in Ultima Online, the religion is based on the ideology of The Virtues rather than on theology. They are what is believed to be the 8 aspects of a good life. The Virtues were introduced by Lord British, under the guidance of the Time Lord. They believe that the multitude of shards can only be reunited if they become one through the Virtues, that if all their inhabitants become one with their counterparts on the other shards in mind and in hearth, they will be reunited in body.

Linking the Virtues are also 3 Principles - Courage, Love and Truth. To keep these Principles, the construction of 3 keeps was ordered. The Empath Abbey protects the flame of Love, the Lycaeum holds the research Truth, and Serpent's Hold holds Courage.

To each Virtue is associated a city, which lives around it. Each Virtue also has an opposite, a taint, which is also the name of a dungeon in Britannia (except for Pride). Lord British has ordered the construction of 8 shrines, one for each of the Virtues, scattered accross the realm. These shrines are magical and will resurrect lost souls that come to them, but only those of good or neutral notoriety. (Except the shrine of Chaos, which resurects anyone).

Furthermore, each Virtue has a color and a mantra.

The 8 Virtues, with all their associations are shown here:

Virtue	Compassion	Honesty	Honor	Humility	Justice	Sacrifice	Spirituality	Valor
Symbol
Town	Britain	Moonglow	Trinsic	Magincia	Yew	Minoc	Skara Brae	Jhelom
Companion	Iolo	Mariah	Dupre	Katrina	Jaana	Julia	Shamino	Geoffrey
Class	Bard	Mage	Paladin	Shephard	Druid	Tinker	Ranger	Fighter
Dungeon	Despise	Deceit	Shame	None	Wrong	Covetous	Hythloth	Destard
Anti-Class	Brigand	Daemon	Gargoyles	Noble	Goblin	Not Available	Not Available	Dragon
Anti-Virtue	Despise	Deceit	Shame	Pride	Wrong	Greed	Sacrilege	Dastard
Mantra	Mu	Ahm	Summ	Lum	Beh	Cah	Om	Ra
Color	Yellow	Blue	Purple	Black	Green	Orange	White	Red
Derived from	Love	Truth	T/C	None	T/L	L/C	T/L/C	Courage

Arguing that the Virtue system was not upholding the individuality of each citizen, Lord Blackthorn created his own Virtue, Chaos, and erected the corresponding shrine in a bold act of protest against his liege and friend Lord British. For the sake of diversity the Chaos shrine will resurrect anyone. 

More recently, the founding of the Guards of Virtue announced yet another chapter of the conflict tearing apart the friendship between British and Blackthorn.

A third doctrine also emerged in the realm, Balance. The principle of Balance embodies both Chaos and the Virtues, good and evil. A hidden city, Wind, was founded on the principle of Balance. It is mostly inhabited by scholars and scribes, and soon became the city of knowledge. Wind is an underground city, and the entrance was made accessible only to learned mages.

More information about the Virtues

Codex of Ultimate Wisdom