I think we have found our point of fundamental disagreement. You mention a lot about moral decisions, what are right and wrong actions, which indicate to me you see some overall purpose to what us little humans are trying to do on this planet.

Without seeing that purpose is relative to the individual you will always see subjective value theory as lacking in some way. I think we can forget about using this as a premise for further discussion, and focus on the validity of the statement "there is no objective purpose in the world" itself.

I'll again read through your reply and attempt to address some of the points directly. In the mean time maybe you could answer the following (which may help me understand why you see my statement as a contradiction): What is the purpose of one's life? What is the purpose of society?