[kosta50]

St. Paul is simply saying that it is not our job to return evil for evil. If any punishment is to be meted, it should be deferred to God.  Burning coals are routinely used in the OT as something unpleasant, so any suggestion that it may be a source of comfort would be contrary to the sources he uses.  There is a presumption, however,  in what St. Paul is saying, namely that God will punish our enemies because they are our enemies. Nothing could be further from the truth.

[monkfan]

There is a presumption, however, in what St. Paul is saying, namely that God will punish our enemies because they are our enemies.

If a person assumes themselves to be a member of the elect, as some tend to do, then perhaps it's only "natural" to also assume that the enemy is reprobate. In which case, something reminiscent of fire and brimstone might seem like a "perfect" solution.