Is there something like the Saint Template from the 3.5 Book of Exalted Deeds in Pathfinder (3rd party stuff included)?
There's a few Templates that are sort of Good-ey, there's a few prestige classes that are saint-esque, but there's nothing with either the mechanical whammy or the horrifically extensive roleplaying requirements of the 3.5e Saint template.
A complex mixture of Pathfinder classes, spells, abilities, racial options, could produce something mechanically a bit like the Saint template's abilities, albeit slower (as there is no direct analogue and the optimizable abilities in pathfinder don't really mimic the 'defensive' nature of the saint template very well), but there is no good direct analogue.
Porting it directly might not be possible as the flat bonuses and abilities the Saint template grants (like the Vow of Poverty feat) probably look 'too powerful' to GMs with weaker mechanical understanding of the game. Nonetheless, it's probably the only way to preserve that mixture of flavour and effect.