Is Doing the Right Thing a Sin If You Truly Believe It’s Wrong?

Questions about whether Romans 14:23 means that doing the right thing is a sin if you truly believe it’s wrong, and how to reconcile Hebrews 10:16, which says God will put his laws on our hearts, with Romans 7:7, which says that if it weren’t for the Law, we wouldn’t know sin.  

• How should we view Romans 14:23 when it comes to people whose consciences have become twisted to the point where they start believing right things are actually wrong? Would doing the right thing become sin for them if they do it while truly believing it's wrong?
• How do you reconcile Hebrews 10:16, which says God will put his laws on our hearts, with Romans 7:7, which says that if it weren’t for the Law, we would not know sin?