Here are a couple theme ideas...let me know if you like any or have other thoughts!!
I want to decide fairly early because I do not like to go out and purchase items for the theme - I usually create them. :) I especially like to create the name tags for desks, homework labels for the board, etc. Every now and then I will buy borders, but sometimes I use scrapbook paper or napkins with the colors I want.
Wisdom - Owls (I still have a few large owl things, and ideas saved for owls/birds
Working together - Gears/Robots 7049.jpg (all things work together for good...)
Soaring to new heights - Bird http://www.schoolgirlstyle.com/2011/09/bird-theme/
Fruits of the Spirit - Just use colored theme with words
Relying on the Lord - surf theme
Faith, Hope, Love - just use colored theme - add black/white?
Teamwork - Gears/Robots or Amazing Race - around the US?
Teamwork - sports (make sure 4th isn't doing...did they do last year?)
I think that's all my theme ideas for now...I may think of more. I think you can do almost any theme. Again, I like to focus on the colors. I usually get black sheets for the bulletin boards and use a cute border. Whatever my theme is, I made a few large things to stand out - like the picture below. I know 3rd grade is doing a detective theme, which is something I actually had been planning thinking - but I know 3rd is doing it now so that wouldn't work.