What does it mean when it says in Romans 14:23, "everything that doesn't come from faith is sin?"

Many people don't understand faith, and think of faith as an intellectual thing. Faith is dependence upon God. God wants us to live in dependence upon him. The opposite of that is independence of him. Independence of God is sin.

So, it's not that every single act I'm conscious that I'm dependent on God. It's an attitude of life where I'm dependent on God, and that's what it's referring to. In fact, one evidence of that dependence of God is we pray. If you never pray, you obviously are not dependent on God. You don't have faith.

But, God gives us freedom in our conscience to do something. That is indication of his will. If you are convicted in your conscience, then that means you should not be doing that.