I wasn't sure what bothered you about it until I saw the thread. And I think you're right. It's sort of worrying that the others in the thread have no idea of what "Son of God" might mean other than the view currently taken by Christians.
Also you should look into Adoptionism, and the Ebionites. But yes, the idea of Jesus as God is only clearly present in John. To say that it is in Mark is worrying, and quite possibly prejudicial.