Modern music is an acquired taste. Actually, all music is an acquired taste. I can't think of a single piece that I fell in love with the first time I listened to it whether it was Bach or Bartok. I can think of several pieces that I abhorred the first time I heard them only to really enjoy them after listening to them a few times. I wasn't wild about the Sibelius violin concerto the first time I heard a recording of it, for example, and now it is one of my favorite violin concerti. Same story with Beethoven's Ninth Symphony and Stravinsky's Petroushka, which are two of my “desert island” pieces.
No matter if the orchestra is playing Messiaen or Mendelssohn, there are easy things you can do to make your concert going more fulfilling. Check out the program beforehand. If there is a piece or two that you aren't familiar with, find a way to listen to them. The public library is a great source for classical music recordings as are the various online sources of MP3 files. Read the program notes either online or before the concert starts. Often times there is information about the pieces that is crucial to understanding the music. An example of this is Messiaen's Les Offrandes Oubliees, which we will be performing tonight. Messiaen wrote the piece in three distinct sections that are played without pause. The sections represent Christ's sacrifice, human sin, and the Eucharist. It is certainly possible to enjoy listening to the piece on its own, but knowing what Messiaen intended to depict adds a whole new dimension to the listening experience.
Two other ways to become familiar with the music prior to the performance is to listen to Lucas' podcast and to attend the pre-concert chat. I am a big fan of the pre-concert chat. It is free to anyone with a ticket and is held in the theater an hour before the performance. Lucas talks about the pieces we will play and often plays snippets from recordings so you know what to listen for. When we have a soloist they will sometimes join in the pre-concert chat which is a fun way to get to know more about them than what they publish in their bio.
Remember: all music was once modern music. A piece that you dislike the first time you hear it may well turn out to be a favorite after you get to know it better.