Sacred cow. A sacred cow is something that has become holy, untouchable with no valid reason. There is a place for sacred cows.
So, what do we do with the ordinance of the red heifer in Numbers 19? Is it a sacred cow to be grilled or something valuable to study?
The red heifer instructions are one of those weird spots in Old Testament Law. These specifications for an animal that you are going to burn and mix the ashes with purification water are very intense. They also leave a lot of questions that are not easily answered.
One question that I have is this: is the ordinance of the red heifer something that was done once or occasionally? Did this happen once and then they just passed on what was left, mixing in new oil/water/spices and claim connection to the heifer, or did they keep a herd specifically for this purpose? The Jewish traditions record it as a rare event, occurring fewer than ten times.
These details could consume us or drive us to ignore the text. I think another detail would be to obsess over what was a “red heifer.” This could be a specific breed, but more likely this description looks like an animal that would be a rarely, naturally occurring animal. That appears to be the more likely case.
Without doing all the research that would go into a book, I would guess that there were traditions that a red heifer showed up just about the time one was needed. This could have been the case, but we do not have any Scripture to back that up. What we do have is Scripture that details very specific ceremony. As with much of the Pentateuch, those instructions were not meant to be taken lightly, but followed to the letter.
What does it do?
Personally, I think this is a ceremony that is intended to meet superstition head-on. It is a Law given by God for two reasons. The first is this: rare, natural phenomena take on mythical status. Think about how we treat a four-leaf clover or talk about blue lobsters, white stags, giant catfish. These almost become objects of veneration, even in modern times.
Ancient times were often more likely to go that route than we are. God blunts that superstition: even a mythical creature is simply a part of the sacrificial system. And what is the sacrificial system? An intricate pattern of worship designed to remind the Israelites of the holiness of God and their dependence on Him. So, the red heifer is clearly placed as part of that system rather than becoming a good-luck charm.
The second reason is closely related: the purification rituals of the Old Testament were intended to show just how difficult it was to atone for sin. The requirement of a spotless, rare animal to even begin the system would have shown the people that sin was not something to be taken lightly. It would have perhaps been a little intimidating: if we screw this up, when will we get another cow?
In all, this is the major point to take note of: sin is serious, and it cannot be simply ignored. For the believer in Christ, chapters like the red heifer instructions remind us of the sacrificial death of Jesus on the Cross. Rather than needing to find the right cow, we need to find the right Savior.