Cheiromancer, thanks for the nice quotes...saves me some time!
Saveomagy
While it is true that both confession and the atonement spell have similarities, they're hardly the same thing.
Atonement
This spell removes the burden of evil acts or misdeeds from the subject. The creature seeking atonement must truly be repentant and desirous fo setting right its misdeeds. PHB p201
Sacrament of reconciliation/Confession
The Catholic sacrament of penance and reconciliation is the method given by Christ to the Catholic Church by which individuals may confess sins committed after baptism and have them absolved by a priest...In order for the sacrament to be valid the penitent must do more than simply confess his known mortal sins to a priest. He must a) be truly sorry for each of the mortal sins he committed, b) have a firm intention never to commit them again, and c) perform the penance imposed by the priest. Also, in addition to confessing the types of mortal sins committed, the penitent must disclose how many times each sin was committed, to the best of his/her ability. Catholic Catechism post Vatican II
As we can see,
Atonement is essentially the D&D version of the sacrament of confession and reconciliation, and if you compare the texts further, you'd find that the requirements of Divine foci and prayer beads closely mirror the practice in not only the Roman rite, but the simliar practices in the Anglican church and Eastern Orthodoxy (which requires the sacrement be performed in the presence of an Icon of Jesus).
Look at it from the deity's standpoint: Clerics and Paladins are his representatives on earth. What good deity in his right mind would reward an expressed and avowed devotion to the deity that is beyond most of his clergy and other faithful
by stripping away his powers by denying him the use of a Divine Focus? The denial of the game mechanic of the Divine Focus removes the ability of the Cleric (and to a certain, lesser extent, the Paladin) to perform many of the basic and core duties of being within a church heirarchy.
Okay, following that line of thought, if a VoP Paladin's church asks him to quest for Evilsbane, a mighty Artefact Holy Avenger sword that in the hands of a paladin of his faith is the only hope to defeat the marauding demon army that is destroying the kingdom, he can use the sword to attack the demons without violating his vow?
The VoP is a Sacred Vow
to the deity the PC serves. It is evidence of the extreme devotion the PC feels for his deity...essentially "I give up everything to follow you, O Shining One." The benefits are a 2 way street- the ascetic gains abilities to compensate him for his sacrifice, and the deity gains an exemplar on earth to whom people can point and say..."Man, I want to be like that...", drawing others to belive.
Presumably, the Shining One is not interested in having demons overrun the world. He sends the Ascetic Paladin on a quest to recover Evilsbane (for whatever reason, the Ascetic is the only representative of the faith who can be called upon for this duty). Presumably, Evilsbane is to be used by one of the Shining One's Paladins, of which the Ascetic is one. However, the Ascetic feels it is not his place to use the weapon, except as a last resort. Thus, the Ascetic will not use Evilsbane until he is given no other choice- be it the death of all other Paladins of his faith in the area, or having the demons change their plan and actually launch a preemptive strike on the Ascetic and his party- and he may even try to keep his vow until he is the last man standing...
But in the end, the deity (in the form of the DM) should not put the Ascetic in the position of keeping his vow and dooming the world or saving the world by breaking his vow, since defeating the demons and keeping the vow are
both duties to the same master. In other words, while use of Evilsbane may technically violate the VoP, the one who adjudicates the Vow and his Paladinly powers would most likely give him a pass on this one.
Real world religion!=D&D religion
Saint != D&D style Vow of Poverty feat.
To which we could add Saint PrCL!=RW saint, but my point is what were the various Sacred Vows and the Saint PrCl emulating- what were their primary inspirations and models- if not the saints and other holy personages of various real world religions?