Ecclesiates reflected a lot of my own personal thoughts and put them on paper. Solomon is the ultimate nihilist, and speaks the truth about the world. There are no blessings, no curses; just the material, the mind, and the reaction to every thought/action.
If you take time... with patience... read Genesis as well. Just the creation story alone. Ask a timeline to be created. Recreate the scene, from the Bible alone, no commentaries. As Cantleave said, total bullshit.
Neverknew, another thing to consider for your friend is that 'awakenings' depend upon the person. Sometimes you can't get through to a person via logic soley; there is an emotional aspect to belief as well. Most of the Law of Moses was harsh and unforgiving. Ask your friend to put themselves in those situations, like merely picking up wood on Sabbath, for instance.
I know it sounds kind of devious, but you can and are allowed to use emotional appeals as well as logical appeals. Hell, JWs do it all the time.