He is both. “Do not take revenge, my dear friends, but leave room for God’s wrath, for it is written: ‘It is mine to avenge; I will repay,’ says the Lord.” (quoting Leviticus 19:18 and Deuteronomy 32:35) This is demonstrated by the relationship between David and King Saul. Based on what Saul had done to David, including outright attempted murder, David had every right to defend himself and had multiple chances to exact, not just revenge, but justice by killing Saul. Yet, he refused. He also punishes: “He punishes them for their wickedness where everyone can see them, because they turned from following him and had no regard for any of his ways.” Job 34:26–27
If a person does not accept the Biblical narrative or the Biblical God, he must find another standard by which to judge the Biblical God’s decisions: are they just or unjust? The problem with that is, every other moral system will prove ultimately relative, so God’s actions will simply fall along a continuum of pleasant vs unpleasant, culturally acceptable or unacceptable; in other words, purely subjective.
If a person does accept the Biblical narrative, or simply wishes to use the Biblical standards of justice by which to judge God, he runs, yet, into another problem: The God of the Bible is the creator of those standards; therefore, he is not bound to them in every way that we are. A family has “rules of the house”. The parents, as the ultimate authorities in the family have every right to make rules that may not apply to them. For instance, they provide all the benefits of living in that family: clothes, food, shelter, entertainment. If they choose to farm out all the chores to the kids, that is completely within their rights to do so. “But DAD! You never cut the grass!” “No, son, and YOU never pay the rent!” Likewise, God is the giver and sustainer of life; therefore, it is his right to take it…in any way he sees fit.
Our greatest problem is we compare out limited knowledge with the knowledge of an omniscient God. We think he’s like us, that he doesn’t have any special abilities or capabilities to “read people”; so we see him as “striking people down” willy-nilly, left and right, all through the Bible, with nary a thought as to their actual guilt or innocence—or what he might be saving them from (the children who died in the flood).WE might see a mild, kindly, non-threatening old man down the street who putters around in his garden, has the best Halloween candy, the best Christmas lights, etc. and think, aww, he’s so sweet! GOD sees his heart, which may be full of sheer hatred for minorities and Jews, murderous in his private thoughts, perhaps, even, a concentration camp guard in a “previous life”. How many times have we heard the same old words by the surprised neighbors of a person discovered to have multiple bodies piled up in their basement or literally fertilizing the flower beds: “He was such a nice man. Kept to himself, always had a kind word and a smile”? Dennis Rader, the BTK Killer, fooled many for years. He was a member of Christ Lutheran Church, had been elected president of the church council, and was also a Cub Scout leader! (BTK, btw, stands for “blind, torture, kill”, his m.o.) So, if we accept that God has PERFECT knowledge of all of us, it becomes less “troublesome” to accept that his judgments and decisions are perfect.