Going to war for God will be with us

Deuteronomy 21:1-20
Going to war , do not be afraid of them, because the Lord your God, who brought you up out of Egypt will be with you. When you are about to go into battle, the priest shall come forward and address the army, encourage them
The officers shall say to the army, if anyone who built a new house, planted a vineyard, become pledged to a woman and not married, let him go home. Any man afraid of fainthearted? Let him go home so that his brothers will not become disheartened too.
When you march up to attack a city, make its people an offer of peace. If they accept ad open their gates, all the people in it shall be subject to forced labor and shall work for you. If they refuse to make peace and they engage you in battle, lay siege to that city. Put to the sword all the men in the city. As for the women, the children, livestock, you may take these as plunder. This is how you are to treat all the cities that are at a distance from you.
However, in the cities of the nations the Lord your God is giving you as an inheritance, do not leave alive anything that breathes. Otherwise, they will teach you to follow all the detestable things they do in worshiping their gods, and you will sin against the Lord.
Why?
The Lord teach Israelite the strategy of the war or the rule of the war.
Going to war is fight for the Lord and the wars are good to the people of the Lord. The promise land need the people of the Lord to flight, them they can get it.
We are working with the Lord, the Lord the leader, we follow his instructions will be perfect.
How?
Be a christian, do not be afraid during daily life, we will have many difficult and troubles, that we have to flight, remember the Lord is with us, if we trust in Him, we may conquer all this and get the promised land. Our life could be a good witness for others.
Right now I am facing a new task, don't be afraid of it, with the blessing of the Lord, I will do it a good job.