For us, salt is just another condiment. It’s spilled on floors, over-used on BBQ, and examined at restaurants by germaphobes before placed on their food.
But in the ancient world, salt was treasured. Whereas today you can buy pounds of it for a few dollars, two-thousand years ago, salt was your paycheck, in some cases.
There are two primary reasons why salt was so coveted. First, it makes food taste better. Contrary to popular opinion, salt doesn’t actually have much flavor of its own—what it does is extract the flavor of the food itself.
This is one of the reasons that Jesus calls His followers the “salt of the earth” (Matthew 5:13). We are designed to bring the goodness out of people—that holy part of every man’s soul that desires a relationship with God.
But the other, more dominant reason that Jesus calls us that is because of salt’s preservation qualities. Food that was salted didn’t have to be thrown out earlier, which would save money. Even if the salt was expensive-ish, it would pay for itself in lower food waste.
What does any of this have to do with the covenant of Numbers 18:19? It seems odd to just throw that idea in the middle of a discussion about priestly provisions, but the idea would’ve been well-known to those cultures, especially Israelites.
Way back in Leviticus 2:13, God instructed all of His sacrifices to be offered with salt. In saying this, God is zeroing in on the preservation quality of salt. The offerings made to God are made with the intent—both physical and metaphorical—of eternal devotion to one another.
Another quality of salt that’s particularly important is that salt generally doesn’t decay, unless it comes into contact with other ingredients. In theory then, salt could last forever as long as it’s not contaminated by anything else.
What would cause the “covenant of salt” between God and His people to go bad? Easy: sin. As long as the gifts offered to God were pure and according to His commands, everything was fine.
And, jumping back to Numbers 18:19, as long as the priests maintained the holiness of the Tabernacle and Temple and didn’t allow sin to enter, everything was fine. Those blessings enumerated in that chapter would remain theirs.
Of course, we know what happened. God’s people played the harlot with other nations, “contaminating” their salt covenant and causing it to spoil.
The priests were the same way. The Old Testament is rife with accusations of bribery (Micah 3:11), sexual immorality (1 Samuel 2:22), and blatant misleading of the people (Jeremiah 5:31). The covenant of salt can’t continue under that arrangement.
But in Numbers 18:19 at least, the outlook is good. God made these promises to His people with the promise that He would stand by them forever. The fact that it fell apart wasn’t on God, but with the people.