I searched threads trying to find this subject, but couldn't find anything on this: I recently joined a tournament that I didn't realize was a thematic tournament. If I resign before making a move, will it effect my rating?

From what I understand, once the tournament starts, whether you make a move or not, you will take the hit to your rating. 

Rating is one matter; abandonment %age is another. Not sure what the rule is, but you don't want to screw that up.

Resignations always affect ratings.

More than three moves (six ply) are required before a timeout affects ratings.

You may think then to let the games time out to protect your rating but it is extremely difficult to lower your timeout %. In comparison a rating is easily recovered.