John at HWS reposes the Numbers 5 question, and gets a good answer in the second comment.
I’d say something like this:
The Bible is a very odd accumulation of writings. The value of much of it is clear, such as the Gospels or the epistles. To the ordinary reader, the value of some of the Old Testament, however, is not as clear, and anyone who reads parts of the early history of Israel, and some of the case laws and rituals, will reasonably ask if they are supposed to believe that God- the God Jesus tells us about- is the same God who is ordering people to be hacked up and women to be given bitter water tests for adultery? To not ask that question is to be a poor reader and not serious about the question “What is God like?”
If you have a “flat Bible” view that says all of scripture is inspired in the same way with equal significance, then you have a problem in passages like this that I can’t solve. I don’t believe in such a view of inspiration. I believe that, on one level, the Bible is a totally human record of things people believed and did. I’m unclear to what extent God was actually involved in some of the violence and cruelty ordered up in the Old Testament. But my approach basically works out this way:
God chooses a man (Abram), and turns his family into a nation. God covenants into a relationship with this nation. The purpose of that covenant nation is to know, worship, and demonstrate particular truths/realities about God. This would include his character, attributes, holiness and mercy. Clearly, this is a process with a lot of risk, and a lot of imperfection. The “chosen people” demonstrated an understandable tendency to resist the entire project at times, and to go fanatical in pursuing it at others. In all of this, God is teaching and shaping them through leaders, events, experiences and laws. The Old Testament is the record of that process, and even with its considerable record of imperfection and many outrageous passages, one can still see and hear God and what he is doing. When we arrive at Jesus, we see the point of it all.
In the law, in particular, God often ordains things that seem extremely strange. Given that this was a primitive and prescientific culture, rituals like Numbers 5 probably seemed fairly ordinary at the time. But the purpose at the heart of the matter is clear: God is a God who requires fidelity to his covenant, and who will try the heart to judge by truth. This lesson is repeated in many ways, and forms the backdrop of a great deal of covenant imagery and prophetic communication. It is an essential lesson, and God chose to teach it in ways that primitive people would understand. A lecture series apparently wasn’t considered.
It is fascinating that later in the Bible, Jesus is confronted with an adultrous woman in John 8, and with the claims of the crowd to have an absolute right of judgment. The well known result was, basically, an appeal to God’s knowledge of every person, and a demonstration of his righteous mercy.
In general, what we begin to see in a stumbling, imperfect, and often culturally primitive way becomes clear in Jesus. He sees our sin. He takes our sin. He is killed for our sin. He gives us his righteousness as a gift. The “bitter water” of the cross is the premise of the “Good News” of the Gospel. The humiliation of a possibly innocent woman prefigures the humiliation of an innocent savior. Like so many of the outrageous OT passages, when we get to the cross, things become clear. Painfully so.
God reveals himself IMPERFECTLY in the Old Testament record, and passages like
Numbers 5 are part of the OT “yearning” for God to come down and reveal himself in a way that is accessible to all who would believe.
We don’t need to apologize for such passages or to attempt to make them what they are not. They are the rough, beginning steps of the record of God making his Holiness and mercy known to the world through his people, but this is a very primative and tentative step in that revelation. When we come to Jesus, and take him back with us to Numbers 5, we can be grateful that the law came through Moses, but grace and truth came through Jesus Christ. Truly, this chapter is a “dark shadow” of the better things to come.