Track not buying protection from a priest as a conduct, as a weaker version of atheist.

In variants where you can gamble away, sell, or otherwise lose your soul: a character who has lost their soul will get no more help from their god (until they manage to recover it). Sacrifices will be accepted but will never get rewarded with a gift; otherwise successful prayers will fail to give you shimmering-light invincibility, will go unanswered, and will give you no message as to the pleasedness of your god, and possibly you lose your divine protection as well.

After some point in the game (perhaps when you descend below the Valley of the Dead and first “enter Gehennom”), you can no longer buy protection.

If you get hit by something reflectable, have no other source of reflection, and prayer timeout is 0, your god may rarely intervene (“But it reflects somehow!”). This could either increase timeout a smallish amount or not increase it. Does not break atheist conduct.

Alternatively, instead of “using” prayer timeout, automatically spend a couple points of divine protection. Because you would have had to break atheist to get that, the atheist problem doesn’t apply.

Permanent alignment conversion prevents you from receiving any more protection by donating to a priest ever again.

When you try and fail to wear a helm of opposite alignment in the quest branch, you only lose all your protection if you had it identified as a helm of opposite alignment.

The cost for buying protection is based on your maximum level reached, not your current level, to prevent draining for gain.

It costs more money to donate to crossaligned priests for protection.

If you have divine protection and become near death from a timed instadeath or low HP, some or all of your protection may automatically convert itself into a cure: “You suddenly feel the power of [deity] surround you! You feel limber/cured/much better/etc.” This should probably work for a narrow range of symptoms (probably not HP loss, possibly any major trouble), and the help delivered should be strictly worse than a prayer if possible (because having this trigger will not affect your prayer timeout).

It should also probably not work in Gehennom, and a key factor is that it should not be reliable, either. Possibly, also track which gods you got it from; protection from donating to crossaligned gods (especially Moloch) will trigger less often.

A slightly more extreme version of this idea is to make divine protection no longer grant AC at all.