Every diety has a favor pool which can be increased by followers praying and doing sermons. As this favor builds up, eventually players can work together to cast global spells (Rite spells). On average, it takes about 8+ months with our current population to build enough favor in order to cast any of these Rite Spells.
Once a diety favor reaches a value above 200000 points a global spell will be made available. Each Rite spell will consume 100000 of those points. A prayer adds 1 favor point. A sermon adds per listener 1 favor point, but more points are awarded for a rare and high quality altar.
forum.wurmonline.com/index.php?/topic/171230-personalising-global-cast-favor/&tab=comments#comment-1746757)
Prayers grant 1 deity favor. No conditions. You don't need to gain faith, adjust your alignment, whatever. A successful pray grants a deity favor.
Sermons are a bit more tricky. They grant 1 favor per person who affects the faith of the player holding the sermon. Think of each 0.02 faith gained as a prayer in this scenario. Furthermore, the rarity of the altar will add an additional deity favor per rarity level. +1 for rare, +2 for supreme, +3 for fantastic.
In a situation where you hold a sermon for 6 subjects and obtain 0.12 favor, you would be adding 6 deity favor to the template deity.