I've always had a little trouble with the way the people of God took over the Promised Land. Why did God want them to destroy everything and especially everyone? I've always understood the destruction of Sodom and Gomorrah, these cities were extremely wicked. So God brought fire down upon them. But was Jericho and Ai and Jerusalem filled with wickedness? Why were they not given a chance to repent? Why weren't they offered a treaty?
This directive given by God is very different than the God of the New Testament. God is Love. For God so loved the world that He gave His one and only son, that whoever believes in him should not perish, but have everlasting life. Where is that God in the Old Testament?
I don't think I have it all figured out, but here is my take for now. God is God. He is in control. He did not have a mid-life crisis somewhere before the New Testament was written. He is still the same God. He is still the same today. He was and is still a holy God. He is incapable of sin. He must punish sin. One of the pillars of the Law is that you should have no other gods before God. I believe that God was compelled to destroy those cities because of their idolatry. In the Old Testament dispensation there was no other way. This sin must be punished. Now since Jesus has been in the world there is hope for everyone. God will allow us to live today so that we might choose to accept the gift of His grace. I don't see any other reason why He would be so harsh in the Old Testament time and why He would be so loving now in the New Testament era. Now there is an alternative. He is still the same God, but with more options.
May I ever be aware that God is a holy God. May I ever be aware that God is a loving God.