Since your historical argument utterly fails, let me turn instead to the Biblical applications.
You seem to have argued that God's actions don't apply to ours (he can do it, we can't). However you seem to have done it within the scope of God the Father.
The first thing I'd like to point out is that it's CHRIST, in Revelation 9, that speaks death to all who oppose him.
Out of His mouth comes a sharp sword with which to strike down the nations. He will rule them with an iron scepter. He treads the winepress of the fury of the wrath of God Almighty.
Any argument that Jesus was a pacifist fails on this passage alone.
Onto the question, are we to be pacifist?
During his sermon (love your enemies), we must realize the context of what was going on. Jesus even tells us, "love your neighbor". The problem is many Jews had distorted this and drawn an incorrect conclusion of, "hate your enemies". As we see within this context, he asks the question... Don't even the pagans greet the people they are friends with? Christians that just greet their neighbors are no better than the pagans! So he gives a new command, "Love your enemy".
We're to love those who disagree with us, who have a different faith, who do harm to us.
Self-defense was part of the law (yes, it's right there in Ex 22:2-3). In God's eyes, this means for the SAME ACT (taking a life)- there are differences within that act. The differences are intention. Was it done out of personal vengeance, malice, and premeditation? Or was it done by self-defense, or just action? Weather or not this applies today I really don't see as mattering, either way we gain a glimpse into the mind of God: there are degrees and differences of killing and murdering.
We see self-defense in Luke 22 as well, when Jesus places a higher value on swords than cloaks in what was about to go down, telling his disciples to sell their cloak to acquire a sword, if they could. We later obviously see, when Peter uses it, Jesus telling him to sheath it. But this is no contradiction. Even though they had a right (he told them to) to carry a sword, he was not telling them to fight for him. He was willing to go to the cross. He was giving himself up for his disciple's sakes. Much like a man taking on his attacker to protect his family.
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