If first enchanted with Spirit Bond, its healing is increased, but damage taken is reduced after Spirit Bond calculates whether the target has taken 60 or more damage. This combination provides an excellent spike counter for PvP. If Aura of Faith were cast first, however, Spirit Bond will calculate whether the target has taken 50 or more damage after it has been reduced.
In the case of Protective Spirit, Aura of Faith's damage reduction is applied before Protective Spirit's, regardless of the order of casting.
Casting Aura of Faith on a target ally initially while under the effects of Divine Boon will not calculate the healing bonus, but casting another Protection Prayer/Divine Prayer spell on that same ally while under the effects of Aura of Faith will calculate the Divine Boon healing.