A couple of excerpts from an article written by Bill Hybel:
"God is a refuge for his children in times of danger and distress.
In certain parts of the ancient Middle East, where populations were spread out, societies weren't well organized, and judicial systems were few and far between, people kept the law and order by a rather aggressive form of tribal crime and punishment.
For example, if someone in your family lost his or her life at the hands of another person, your family would call a meeting. You'd discuss the situation, then appoint someone who became known as "the blood avenger." This person would become the representative from your family whose job would be to track down and kill the person who killed your family member. Then a celebration would ensue. Justice had been done.
A problem arose in the middle of that culture, however. There was no provision for accidental homicides, for unintentional deaths.
In the Old Testament books of Deuteronomy and Numbers and Joshua, we see God step into this situation. He addresses the problem by establishing cities of refuge. Joshua 20:23 says, "to designate the cities of refuge as I instructed you through Moses, so that anyone who kills a person accidentally or unintentionally may flee there and find protection from the avenger of blood."
God established six cities. They were spread out for easy access. They all had paths going their way and signposts pointing to the city of refuge. If a person committed an unintentional homicide, he or she would take off running. If the offender go to the city of refuge before the blood avenger tracked them down, they were safe inside the gates. After a time, a fair trial would be held. If the person were innocent, he or she would be set free. If the person were guilty, the blood avenger would do his thing.
But look at what God provided in the middle of this situation. He provided a place to run to, a shelter, a hiding place till a fair trial could be had. And look what God named these cities—cities of refuge.
The idea for these hiding places, these shelters, flows out of the very heart of who God is. It is bound up in the nature and character of God to provide safety and refuge to people who are feeling oppressed or hunted down. It is in the heart of God to provide safety and refuge to people who are running fast but wearing down. It is in the heart of God to provide safety and refuge for people who are hearing footsteps and who desperately need a hiding place.
You need to understand that our God is a refuge-providing God. He delights in that role. He only asks that you would avail yourself of the refuge that he provides."