Similarly, they will heal you if you're at 50% health from being sick, but not deal with the condition that took you there in the first place unless you pray again while at ~100% health. Therefore, removing sickness takes two prayers (one for healing, and immediately a second one to actually remove your ailment) if you've had it long enough. Either these priorities should be reversed, or there should be a new prayer result that both heals sickness and heals you to full HP, for a somewhat higher piety cost.

a) the first case is fixed now
b) the second case behavior (heal sick priority) is intended. Healing is considered more important in "emergency situations" than curing sickness, so these priorities are not going to be changed.

But the player is 99% of the time on low HP because of the sickness! Sickness quickly takes your HP below 50%, and cripples your character in other ways, too. Curing sickness is almost always more important for players than simply recovering the HP. Regaining HP is pointless because you will instantly lose it anyway, due to the sickness!

Refilling HP should be preferred to curing sickness only when it's extremely low.

Perhaps healing sickness should be prioritized at 40% HP or higher. But even then there might be cases in which players really need the full heal instead.

Yes, that's exactly what I had in mind.

Ok, guys... I'll discuss this with Thomas again. :)

Perhaps, if there is more than one issue present, the player could choose what they want to pray about?

Allowing the player to choose IMHO is the only serviceable option but it's too big a change internally for now.

Anything else IMHO doesn't work as it is too hard to analyse situations like "the PC is sick and below 40% hitpoints" - healing sickness might be ok if he is not immediately threatened by monsters, healing sickness might be better otherwise. The factors influencing this are too manyfold for a quick fix. ADOM II will try to be much better in that regard :-)

What about having it that you get healing AND cure sickness, but it costs more piety than just healing?

I was also thinking you need to know at least one spell for a prayer to refill your PP, and that virtually locks mindcrafters from praying for power until they find a wand/potion of wonder. There should be an exception for them.