Salt, for us in the 21st century, represents anything from a flavorful additive to our food to the veriest poison that will kill us all to something that's not all that harmful, depending on which cooking show or medical study revision you happen to be reading at the time. But no matter what role it plays, we never associate it with any kind of hardship in getting it -- it's there on the table or in a paper packet or in a blue cardboard canister on the store shelves, always ready to hand.
In Jesus' day, salt had almost only a positive role to play in food preparation. It was one of the few seasonings that poorer people could afford, and it was one of the very few ways to preserve meat for later eating. Even so, it was tough to acquire. "Working in the salt mines" is an old cliché meaning hard labor, referring to the fact that the mineral processed into salt for cooking had to be dug from the ground. People who lived around the extremely salty Dead Sea could gather mineral chunks from the shore and carefully process them to separate the salt from the other substances in the chunks, but if they did it wrong then they had a bunch of useless sludge they had to throw away. This was the kind of salt that poorer people most often used, since the Dead Sea could always produce more mineral chunks and all you had to do was pick one up.
That's probably what Jesus meant by salt losing its taste or its saltiness: Making a mistake with one of those chunks of minerals and ending up with sludge. His listeners would have quickly understood the metaphor.
The metaphor comes to my mind when I reflect on what kind of a relationship I should have between my identity as a Christian and a citizen of my country. As a United States citizen, I live in a nation whose founders chose to reject the idea of a state religion. No governmental agency can act in a way that prefers one religion -- or any religion at all -- to any other. That's the "establishment clause" of the First Amendment. Neither can government make laws that tell me how to practice my religion, unless that practice conflicts with the basic rights of others. This is why I can't move into your house and claim you can't evict me because my religious practice mandates I live in strangers' homes -- it conflicts with your rights to enjoy and safeguard your own property. This is the "free exercise" clause.
Today, one of the most common ways of expressing the First Amendment protections is to use Thomas Jefferson's phrase "separation of church and state." And what it seems like most people mean when they say that is that I, as a religious person, should keep my religion to myself. I can pray, practice, preach and believe whatever I want while I'm in my own home or with like-minded people, but I need to leave all of that at the door whenever I exercise my duties as a citizen.
So in order to honor this understanding of the First Amendment, I need to vote without respect to my religious beliefs and allow them little or no influence on such decisions. If I participate in some program to help other people, I need to do it without any reference to my Christian faith and practice.
You can see how this breaks down. There are plenty of non-Christian folks who do pretty well at helping others and plenty of Christian folks who do pretty badly, but I know that I wouldn't help people nearly as often as I do if I wasn't a Christian. Jesus' call to me underlies my understanding of how I relate to everyone, people in need or otherwise.
If I believe that a free-market economy with as little government regulation as practical is the best way to help poor people rise from poverty, then I should vote for a candidate who follows those policies too. If I believe a social-democratic welfare state is the best way to do that, then I should vote accordingly also. If I do anything else, I've lost my saltiness -- and what good am I?
Paul offered us several pieces of advice on what kind of citizens Christians should be, and most of them center on doing exactly that -- being good citizens until or unless that conflicted with their faith. In a representative democracy that's based on the rule of law and respect for private property rights, we have opportunity after opportunity to properly exercise our responsibilities within the context of our faith. The only boundary is the one that would cross the line to some privilege our faith over other people's and work to impose it on people who don't share it, which is something God doesn't want us doing anyway.
Sometimes folks who don't want religious people, including Christians, to base political decisions on faith understandings and beliefs, say things like "You should leave your God outside the voting booth." But the problem with that idea is that I believe God's already in the voting booth.
The only question is whether or not I'll listen.