There is a great theological problem in our argument that sin ceases to be sin when it is either necessary or the greatest good (least objectionable). That is, there is a great theological problem when the definition of sin becomes circumstantial or situational.
It is no longer grounded in the character of God.
Sin is sin because it is against the heart of God. Sin is sin because it is against His nature, which ought to be our nature if we are to be image-bearers of Him. Sin is sin because it is against God's will, against His intended design, against His greatest hope. When we say that sin may mean something different in one situation than it does in another, we are implying that God does, in fact, change. We are implying that His heart is, in fact, variable. We are implying that His nature is somehow relative.
Let's go back to the example we used yesterday, which is one of the most popular in relation to this question. Is it a sin to lie if that lie protects the life of an innocent person?
The popular contemporary answer is "no." No, it is not a sin to lie if that lie protects the life of an innocent person.
Here's the trouble with that: God says, I am the way, the truth, and the life. He makes a very bold statement about truth here. He makes a very bold declaration that truth matters. How then can we continue to argue that our God is truth if, in fact, an untruth does not offend Him? How then can we argue that God even values truth if, in fact, there are times when He doesn't mind our lying?
See how sticky this gets? And fast!
Any time sin is situational, God ceases to be a firm foundation. He becomes situational, too. He becomes flexible. We bend our God to fit our circumstances, and it breaks His heart. Not only His heart, but His testimony.
When we think about these kinds of things, it feels like the easy answer is just to say that the lesser evil or the greater good or whatever is necessary must not be sin. It feels like it's simple. Because it sounds a lot easier than trying to explain how God would let His children end up in a place where no matter what they do, it's sin. It's easier than trying to explain that there is a place in this broken world where we have no choice but to act against God. (And it feels sometimes like either way, that's the case. If we lie, we act against God's value of truth. If we allow the innocent life to be taken, we have forsaken one of God's beloved, haven't we?)
But the easy answer is not so simple. It creates more questions than it can possibly answer. It diminishes our God. It makes Him just as relative, just as willy-nilly as the rest of us. And then what? Where do we go from a place where God is essentially no better than us?
No wonder this world struggles with our witness.
Although it is more difficult from a heart that must live through the tension, it's actually easier to just be honest about the whole thing - either choice here is sin. We are in an unwinnable situation. Whatever we do - whether we lie or whether we forsake an innocent life - we sin. We offend our God. We break His heart. There is not here an action that God approves of. (And it must be said, nor does He approve of our doing nothing at all. For even not making a choice is choosing.)
It feels messy this way. It feels like this probably sets up even more of a conundrum for us than just deciding that sin may not always be sin, but that's just not the case. When we admit that sometimes, life puts us in these impossible situations, when we embrace that often, we simply must be sinners, we create space for God to do the most wonderful thing: be God. We set Him up to do the very thing that He truly does.
What's that, you might ask? Stay tuned.