According to the Council of Conservative Citizens they most certainly can, and in the case of the Norse Gods that race is white. The CCC has decided to boycott the movie Thor because one of the gods is being played by Idris Elba, who is black.
This issue has already been dealt with perfectly in comic format.
All I would like to add is that I'm not sure people who continue to think that this guy:>
Looked like this:
Really have much place complaining about the depiction of race in the imagery of gods.
Of course one could also point out that, when it comes to Thor, we're dealing with comic book character who fight crime in the 21st century. But, that seems far too rational.