Why did God command the killing of people in the Old Testament?
To answer this question comprehensibly, it is fundamentally important to understand the meaning and purpose of God's plan of creation. God's intention from the beginning was for all people to live in peace and security on earth. However, after humans abandoned God and went their own way, they quickly plunged all of creation into misery. The earth and everything on it belongs to God. But God gave us humans the earth as our possession so that we could inhabit it and live on it in accordance with His will. Then, and only then, do we humans have a right to exist. If we live contrary to God's will, we miss our destiny and thus forfeit our right to exist. For everything humans do that is not in accordance with God's will is sin. God's judgment on sin is death....
Even before the creation of the world, God devised a plan to redeem humanity from mortality and restore peace on earth. To fulfill His plan, God chose a man named Abraham, from whom the people of Israel emerged. Through Israel, God wanted to make His salvation available to all other peoples on earth. After the Israelites had lived as slaves in Egypt for many years, where they were cruelly oppressed, God liberated His people through a man named Moses. Once the Israelites were free, God gave them His holy commandments and ordinances to live by. These were intended to make Israel a model for all nations. In return, God promised Israel His blessing and a fertile land where the Israelites would live in peace forever.
After the Flood, people spread ever further across the earth. Individual clans gave way to kingdoms that claimed power and territory for themselves. War, violence, and oppression were the norm. None of the pagan peoples observed God's commandments and legal systems. Instead, they worshipped false "gods" and performed religious rituals that were abhorrent in God's eyes. The only way for Israel to survive as a free people and take possession of the Promised Land was to defeat the other nations around them. Therefore, God commanded the Israelites to fight their enemies, conquer their cities, and execute the ban on them—that is, to kill or expel all the people within them.
With this, God executed His judgment on all nations who had profaned His holy name. At the same time, everyone was to realize that God is with Israel and that God rewards those who love Him and live according to His commandments. With God's help, the Israelites succeeded in defeating many nations that were militarily superior to them. Finally, Israel was able to take possession of the land God had promised His people. To prevent the Israelites from turning away from God and being tempted to worship other "gods"—as happened repeatedly throughout the centuries—God commanded them to eliminate every trace of pagan idolatry.
The violation of some of the commandments God gave to his people was punishable by death. These included murder, adultery, blasphemy, and other serious offenses. These deterrent measures were intended to educate the Israelites in God's righteousness so that they would learn to worship the one true God, do good, and avoid evil. At the same time, God wanted to prevent people from turning away from Him and ending up in damnation. All the testimonies handed down to us in Holy Scripture are intended to serve as a lesson and to make clear to us how serious sin is in God's eyes. Even if God's judgments seem cruel to some, God fundamentally acts for the good of all people. God's goal is to free the world from suffering and injustice. After all, this is the most fervent desire of humanity. The prerequisite for this is that all people recognize God's will and obey His commandments.
At the center of God's plan of salvation is Jesus Christ, whom God appointed as the Savior of all people. When the fullness of time had come, God sent Jesus to His people to offer them forgiveness of their sins and eternal life. Jesus taught people to love one another and to renounce violence in any form. Therefore, there is no justification for the numerous crimes committed "in the name of God" over the past 2,000 years. To this day, God proclaims His good news among all nations peacefully, so that everyone who wishes can become part of God's people through faith in Jesus and share in eternal life.