Chapter 4 of Divorce and Remarriage in the church is quite short and has one primary point: Just because we live in the NT age, we do not ignore the OT. Jesus clearly comes to fulfill and to expand on the Law and does not speak against any of the OT–only against false interpretations of it. Some quotables:
Jesus called us to take note of every letter of God’s law, so we cannot simply ignore it. (45)
Jesus fulfilled the ceremonial parts of the law on the cross, but he wants us to fulfill the moral parts of the law, and he even said that he wanted us to be perfect like our Father…. he affirms the principles of these laws [in Matthew 5] and widens their application. (49)
Jesus never criticizes what the Old Testament says, though he frequently criticizes the way people interpret it. He condemns the way some people tried to sidestep the command about oaths by claiming that they were not making a real oath if they swore by “by heaven”… (50)
As you can see, Instone-Brewer is telling us that in the next chapters where we look at the NT data, it ought not be seen as in opposition to the OT but as further explanation of the underlying principles of the OT.
As an aside, he explores 3 possible ways people look at the relationship between the OT and the NT:
1. The OT contains ceremonial and moral laws. In the NT, Jesus fulfills the ceremonial by his sacrifice, leaving us with the moral parts. I-B says the problem with this is that we may not agree as to which is which.
2. Christians follow OT moral principles but not the details (e.g., we no longer stone individuals caught in adultery but we recognize the moral principle behind the prohibition).
3. Ignore any OT laws not mentioned in the NT. Problem here is that rape is not mentioned in the NT.
Finally, I-B warns the reader against seeing the OT as legalism and the NT as grace. God is just as forgiving in the OT as he is in the NT.
Not much for me to add to this except to underline his point about the NT expanding and highlighting the principles of holiness. We recognize that the sin behind adultery is in all who ever lust after another. This helps us avoid pride and arrogance. Now from here we’ll look at the NT writings that relate to divorce and remarriage.