Make atonement before the Lord with fire and water

Numbers 31:1-54
The Lord asked Moses to arm men for the war, to execute the Lord's vengeance on Midian.
They killed Balaam the son of Beor with the sword.
The men in the army who had gone to battle have to be purified themselves and therir aritcles outside the camp with fire and water.
Take the count of the plunder that was taken, divide the plunder into two parts between the warriors and all the congregation. One out of 500 of the men of war , give to the Lord. From the people of Israel's half, take one of 50, give them to the Levites.
The officiers devoted each of them found, articles of gold, armlets and bracelets .. to make atonement for themsleves before the Lord. They said "there is not a man missing from us."
Why?
This is a war of the Lord, so God blessed people of Israel, there is not a man missing.
The Lord is holy, close to the Lord have to be purified, so anyone killed any person and touched any slain have to follow commands to clean themselves.
Atonement is doing with fire and water. So the judgement of the final everyone have to be checked with fire. Is our life make by stone, gold or wood, grasses?
Only the blood of Jesus can purify our heart and spirit. Fire and water clean the articles and clothes.
How?
Work for the Lord may unclean during the procedure, so make atonement is needed before come to the Lord.