Perhaps I can give a different perspective to this thread. I have played piano at my church for the past four years. During those four years, I have played many many hymns and praise choruses. I have also played many classical pieces. For some of the people in my church, the only music they get to listen to all week is what they hear me play. They like to hear songs that they can recognize, and hum along with. What I have found works really well is to purchase a book of more advanced piano solos that are "church songs." Word Music publishes several books, and they are called things like "The Big purple book" or the "big Bronze book" I don't remember all of the colors, but those have some great music in them. A man named Mark Hayes has written many wonderful arrangements of music for church. If you really want to play something classical, there are several books called something like "hymns with a classical touch" and they take a great classical piece, and weave a hymn into it. The book I have includes things like Beethoven's "Moonlight" sonata/It is Well With My Soul. Grieg's "Morning Mood"/Amazing Grace.
Hmoll is right about most people coming to church to worship, not attent a classical concert. I am a classically trained musician, and I know that I can worship God just as much by playing a Beethoven sonata as by playing/singing "Amazing Grace." But there are some people that don't realize that, because they don't get the chance to immerse themselves into the piece as they are learning it. Does that mean the don't appreciate it? I believe that means they don't understand it the way you do. Also, remember that these people came to church to be spiritually challenged, and to grow in their faith. That means that by the end of the sermon, God has probably shown them something about themselves, generally something I at least don't really want to see. At that point, music really isn't something that's incredibly important to me. The best advice I can give you is to work on your hymn playing. As long as you can get the melody in there, make up a bass line. Look at the root note in the bass, and then just play that chord arpeggiated. Invest in some Sacred Solo books that sound almost as good as classical stuff. And above all, remember that when people come to church, it's to put their focus on God, not on you, or Beethoven's sonata. It's not an insult, it's just the atmosphere.
Love,
Sarah