Holy righteous people would not murder other people.
Paul says ephesians 6:12 we wrestle not against flesh and blood but against spiritual wickedness.
Also - John 1 says God is ONLY light in Him there is no darkness.
John 4:24 (KJV)
God [is] a Spirit: and they that worship him must worship [him] in spirit and in truth.
1 John 4:1
Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world.
Psalm 78:2 (KJV)
I will open my mouth in a parable: I will utter dark sayings of old:
Proverbs 26:7 (KJV)
The legs of the lame are not equal: so [is] a parable in the mouth of fools.
Considering these scriptures, and many talking about the love and mercy of God,
The scriptures seem to be speaking these types of things in parable form and the enemy of Israel, of ANYONE, is SIN. NOT OTHER PEOPLE and certainly not whole nations of people.
34 ¶ Then Peter opened his mouth, and said, Of a truth I perceive that God is no respecter of persons.
2 Corinthians 3:6 (KJV)
Who also hath made us able ministers of the new testament; not of the letter, but of the spirit: for the letter killeth, but the spirit giveth life.
Reading scripture according to the letter =death.
Understanding it literally, according to the letter will always lead you to death. Either having a good reason to kill someone else or there being a good reason that you should be killed.
But Paul gave us understanding that there is such a thing as reading it "spiritually".
Reading it spiritually is almost like another language.
It's full of symbolisms, metaphors, types, shadows of things.
The first rule of learning to read it spiritually is :
That God is a spirit and concerned with things of the Spirit. There is no confidence in the flesh. This world is not his realm. The 'country' he told Abraham to go to was the kingdom of God In his heart. That kingdom comes with no observation. It is within. In other words..the Spirit.
So you can see that commanding people to kill other nations in the flesh on earth, isn't likely.
I read that comparable to what you could say to an addict.
"Kill off EVERY PART of the bad habits. Do not leave 'occasional usage' as an option. Do not leave 'weekend drinking' as an option. Do not leave 'special occasion usage' as an option.
You have to know EVERY bit of those habits are killed in you. Or it will come back to clobber you over the head."
It's metaphorically talking about having dominion over sin. Sin is crouching at the door ready to devour you so do not leave a single part of it left breathing.
Edited to add :
John 3:16 for God so loved THE WORLD that he gave his son.
It is his will that ALL be saved.
There were no whole nations of people that He hated. God hates sin not people. We all have the opportunity to repent a thousand times a thousand times and be forgiven.