If in truth there is no right or wrong and I can do whatever I please, then can I commit a sin, such as theft or adultery?
You may have liberty to commit sin such as theft or adultery. However, the police, have every right to take action as per law. Now think about what you mean by right or wrong. For smooth functioning of a society, representatives of society or governments have created laws. Actions against the order of law will be punished. Right or wrong is opinion of the society you live in, or it is the opinion of mind. It may not hold well in the divine world or in the society of another nation. Minds differ from person to person, truth differs from society to society, and meaning of truth in the inner world differs from that in the outer world. Outer world of truth is full of illusion and changes from time to time. However, Inner world of Truth always remains the same and one can always enjoy the real truth within oneself.