The deity Ashura seeks to enter the mortal realm using an avatar. This is meant to fulfill a prophecy, in which he does battle with an ancient demon seeking to conquer earth. However, avatars are only capable of possessing a portion of a God's power, making him much weaker in the mortal realm. Ashura decides to manifest his avatar, which would reproduce asexually. The child resulting from this would be Ashura at full strength, with all his godly abilities and powers. This completes the "Blessed Trinity" of the religion that evolved around the god: These individuals are regarded as separate aspects of Ashura: The first being creator of the universe and ruler in heaven, The third as representative of God in human form and eternal king on the material plane, and the second being God's transitory avatar that was re-absorbed after its mission was complete. All three are worshipped as one being and are meant to retain equal reverence to each other.
As the second being in the Trinity is simply a smaller part of the first aspect and is basically a vessel to create the mortal aspect, it lacks a true, separate identity. The fact that it is a temporary figure in the religion that was subsumed back into the creator makes it seem like the lame duck of the group, lacking any relevance to the mythology. With this in mind, it would end up being overshadowed by the other members in the pantheon. As it has served its purpose, there seems little reason to keep it around and pair it with the others. How can this faith be crafted to make this aspect relevant?