The importance of family is highlighted throughout Scripture from its beginning (see, for example, the command to be fruitful and multiply, Gen. 9:7). As important as blood ties are in the Word of God, however, even more important is the family of faith, which consists of all those who by faith believe in the name of Christ and thus are God’s children (John 1:10–13). Not every person is a “child of God” as it is understood in popular culture; rather, since all human beings are born children of Adam — sinners — and not children of God, only those who receive adoption as His sons and daughters through trusting in His promises can actually call God Father (Gal. 4:1–7).
Because adoption into the Lord’s family is by faith, God has always received as sons and daughters all those who believe in and then follow His way, no matter their ethnic or religious background. Since the fall, whenever people forsake the sinful ways of their father Adam and run to God for salvation, our Father takes them as His children. That this was true even under the old covenant is seen in today’s passage.
When the Lord rescued His people from Egypt and sent them into Canaan, He ordered them not to spare any of the residents of the land (Deut. 20:16–18). This was no genocide; God was not against the Canaanites because of their ethnicity but because of their wickedness. If there were Canaanites who wanted to serve the Lord, He would certainly spare them and adopt them into the family of Israel. The ancient Israelites understood this, which is why the spies promised to spare Rahab (Josh. 2). In and of herself, Rahab was no more righteous than the rest of the Canaanites. As a prostitute, she could have been more wicked than some of the others who would be put to the sword. Her only difference from the other inhabitants of the land was that she recognized Yahweh fighting on Israel’s side and that He was the one, true God. By faith she forsook the blood ties she had to the Canaanites, choosing instead to submit to the Lord. Consequently, she was adopted into God’s family (6:22–25).
Rahab revealed her faith in risking her life to hide the Israelite spies (2:1–14). Being a true child of God means being just as willing to lay down our lives for His people as we are for our own kin. Matthew Henry writes, “Those who by faith take the Lord as their God take his people as their people, and cast in their lot among them.”