Romans 14:23b ... "Whatever is not from faith is sin." Anything you do without faith is sin. So when we're not operating in faith, it's a transgression against God.
Romans 1:17 ... The righteousness of God is revealed from faith to faith, as it is written, "The just shall live by faith."
When we do things from our free will in the natural sense without conversing with God about it, we're bordering on sin because it's a transgression against Him. He wants to lead us, but He's not going to dictate to us everything we have to do all day long. He's not legalistic ... He's not going to beat us up if we mess up.
Reverend Robert W. & Mary C. Butler