@Tuna,
I was persuaded to add a religious perspective by the thread's religion tag,
I think the religious edge is quite pertinent, in that depending on the existence of a god and judgement criteria of said god, the end game changes quite dramatically, I am however always happy to consider both angles.
On Christianity's colourful and bloody history, I am sure each and every individual in each and every denomination will answer to their and/or an existing god if judgement is in it's nature according to their actions. I'm not sure that in actions of aggression or violence, they would be fulfilling the standing orders of their patriarch Yehoshua, Joshua, Jesus, whatever his name may be to them. (not sure if I put enough clauses in there
)
With regards to the biblical god's ruthlessness, it depends on how you qualify ruthlessness. When he pronounced judgement on an individual or a nation, he always sent a warning and prepared a way out, even reversing the judgement if repentance was made clear, prime examples being that of the Ninevites as a nation, or Manasseh as an individual. Whether that denotes mercy or not is at the observers discretion.
Perception is a powerful tool, though marred by the many biases we each carry