In Deuteronomy 20:17, God passed judgement on the people living in the land of Canaan and commanded they be destroyed.
“Completely destroy them—the Hittites, Amorites, Canaanites, Perizzites, Hivites and Jebusites—as the Lord your God has commanded you.”
Why was such a harsh command given?
The next verse tells us: “Otherwise, they will teach you to follow all the detestable things they do in worshiping their gods, and you will sin against the Lord your God.”
First thing to note is this command was given to Israel in a specific point in history against specific people. It was not a command to be adhered to for all time. So, the answer to the question is: No, the Bible does not command Christians to kill unbelievers.
Now for the first time in 400 years, they are going to be a free people. But these slaves have no clue what this means. They dont know how to govern themselves or become a nation. They didnt know what was right and what is wrong. According to scholars there could have been almost 2 million ex-slaves people who left Egypt.
They needed laws to guide them as well as to protect them. And God gave them over 600 laws. They needed guidance in every area of their living, including relationships, sanitation, food, quarrels, etc. To us, reading this today, some of these laws may seem weird or even silly but it was for THEM and not for us. And they are recorded in the Torah for us as to read the history of the people of God, not something to be followed forever.
Also, they were coming into the land of Canaan, whose people were utterly wicked. Over 400 years of Idol-worship, sacrifice of babies, everything was acceptable to the Canaanites, killing, raping, prostitution, incest, etc. This is why you find some of these bizarre laws about prostitutes, rapes, etc. It was not that the children of Israel were doing it. It was addressed because of what the Cannanites were doing!
These laws were given to warn the people of Israel not to follow what the people of the land were doing! These laws made it clear that what they were seeing practised by the Canaanites were utterly evil and wrong and the people of Israel are NOT to follow their wicked ways. And if they did, there was going to be severe punishments like stoning, etc as described in some of those laws. The laws therefore protected them and warned them about following the ways of the Canaanites. God knew what was right and what was wrong. The people didn’t. Remember, all that these slaves knew for generations, is to just obey without question.
So can you imagine a bunch of docile ex-slaves, coming into a corrupt evil community?. What do you think will happen to these submissive group of people? Either they will all be killed or they will all become like the Canaanites. Therefore, the Canaanites had to be wiped out. The Canaanites had 400 years to repent. None did. God is a God of Justice. Does God not have the right to remove evil as He pleases? When, where and how, it’s up to Him.
Does God have the right to send judgement on evil or not?
During the Great Flood, he sent judgment on the earth by means of a deluge of water that killed everyone except a handful of His chosen people.
In Canaan, He was sending judgment on the wicked people of the land by means of Israel as His instrument and preserving His chosen ones.
What is the difference?