Zero, I don't think that's quite right. Abilities that add +X to prayer scores require that the prayer score be established prior to adding the bonus. For example, normally you roll the dice, then add +X to the result.
If an effect (e.g. Reverence) causes you to choose your prayer score rather than roll, then simply extend the logic used to apply prayer bonuses normally: derive prayer score (if not by roll, then by choice), then add bonus. (So if you chose a prayer result of 4, then the Priest could turn it into a 5. The effects become redundant because the Priest could simply have chosen 5 to begin with).
As a separate issue, Reverence states, "instead of rolling." This implies, "instead of rolling the dice you normally would roll." Therefore, I think if you paid 1 gold at the High Temple, you would normally roll 1 die, so Reverence would allow you to choose between 1-6. This would allow the Reverence and prayer bonuses to actually be useful together. For example, the Priest pays 1 gold at the High Temple, then casts Reverence, chooses a result of 6, then adds +1 to obtain a result of 7. Casting Reverence at the High Temple essentially allows you to pay 1 gold to get a result of 6 (+ prayer bonus) or 2 gold to get a result of 12 (+ prayer bonus), essentially a "prayer discount."
That's my interpretation.
Edited by Artaterxes, 18 February 2014 - 08:33 PM.