The church of Prios and its representatives were formerly protected by the Knights of the Dying Sun, heavily armed and with the fire of faith burning behind their breastplates. The power of faith makes the armour of the sun knights harder than steel. Their mere presence repels abominations by the sheer radiance of their conviction or by weapons burning with Prios' holy rage.
That is now in the past.
Though a handful of Templars have held true to their oaths and the Curia, under the direction of Iakobo Vearra, the majority of the knights have come to believe that Prios is dead, murdered by agents of the Eternal Night and their allies that spread the poison of heresy into the hearts and minds of decent Ambrian folk. Righteousness has been replaced by fury, prosecution with retribution and there is nothing left for them to do but to avenge their fallen God in any and every way possible.
They have accepted that their lives are forfeit and that their souls are lost. Prios is dead - purity is dead. All that is left to do before the Eternal Night closes over the world is to drag down as many of its servants as possible and, when the time comes and death claims them, to kneel in eternal mourning in the cold ashes of their fallen lord.
Following the events of SY12. The Howling Of Damned Gods, Part II, the party's lives are now forfeit as far as the Fallen Knights are concerned.