Still, I can see why Jon is troubled bit by it, exact correct wording is important as a scholar, even when doing a somewhat informal introduction. I can't say much though, as I do not know much about the NT on a scholar level, only their time of writing and the general audience for each gospel.
Nor am I an expert, but from what little I remember from Bible classes in school 'Son of God' was used in Jewish writings for various significant and important people, like high priests and kings, without this meaning they themselves were gods themselves. Mark was generally considered the earliesyt gospel, and it is also the gospel in which Jesus is the least miraculous. The resurrection bit at the end is often considered a later addition.
By the time we reach John, the latest canonical gospel, there's all sorts of magic and hocus-pocus, and Jesus there is clearly God. But there's a school of thought that Mark was not about a literal son of God, but just a holy man. The story grew in the telling.
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