I'll start by saying you have some great cartoons. If you are not already doing so, you could certainly have a career in illustration!
It's a nice clean design, my favourite. I'm glad to see you're taking into consideration other's ideas.
I don't really know what the site is about. It's not immediately obvious, and if that's not portrayed in the design, it should be portrayed by a slogan, or an about us paragraph somewhere on the homepage. Maybe slot it under the Welcome to Wisdom Theory text and put a border round it to distinguish it in the page.
The area above the main graphic is a little bland. I would suggest either shrinking it down height wise, or moving the Adsense up there (and boost your profits at the same time!).
I'm a fan of the navigation design. Pleasant colours and nice font. It might be a personal preference but I think people generally expect the navigation above the main graphic. That might also help your header problems.
Finally, a forum is a good idea for the topic, but you need to get a few more members in there. Really try and push that. You should also slot the main navigation bar at the top of the forums for continuity so people can get around the website from the forum.