I have taken the liberty to taking the Priesthandbook before me (page
120 - 121). Not that I fully agree with wat is in here, but then you
know TSR's official view on the thing. In it there are four kinds of
catogeries of divine punishment a priest can get:
*Minor offenses
*Inappropriate weapon and armor use (not really appropraite for Belinik)
*Betrayel of Goals
*Divine Retribution

Minor Offenses - Not much detail on what a minor offence is. It is
punished by withholding some spells or powers for a view day's, just to
make a point.

Betrayel of Goals - "The first time this happens, the god will give the
priest an unmistakable warning. This could be a heart attack, costing
50% of the priest's current hit points. It could be a portentous
destruction of a statue of the god while the priest is present. It could
be an earthquake or other warning. The warning doesn't have to
immediatly after the betrayel, but will soon after.
The second time this happens, the god will appear to the priests. It
doesn't have to be in person, right then; it might be in a dream, the
night following the betrayel. The god will sternly ask the character his
motives and order him to return to proper worship.
!The third time this happens, the god will immediatly reduce the
charater to 1 hp and CHANGE his character class. The priest will become
an ordinary FIGHTER at an experience level two LOWER then the priest's
level (minimum first level); his normal hit points total and possessions
will be unaffected. Until the character undergoes a severe ritual of
atonement, the god will despise the character and plague him with little
ills, diseases and enemies. Once the character attones for the deed, the
god forgives him...but the character will still be a FIGHTER."

Divine retribution - You don't wanna know (the change of class is the
minium punishment and death is also a minor punishment).

I personally think that even evil deities like Belinik will give an
offending priest two chances before giving final punishment. They have
allowed the priest to enter their services afterall and retaking that
privelege, is a loss of face for the god also. They made an error in
judgement afterall. I also think that Belinik would not punish the
character with death, that seems way to forgiving for him. Taking away
his ability to fight and then making him a slave seems a lot more along
his lines.

Pieter Sleijpen