You can be a choral director without knowing the ends and out of musical theory. You aren't composing the music that your choir will sing. You are interpreting it, bringing the musical intentions of the composer that are on the written page to life through your singers. You will need to balance chords that are divided between the various voices, but you will not have to analyze those chords unless you want to.
EDIT: When I think of music theory, I think of all that analyzing of chords from the first chord to the last chord of a composition. This is very important for those who want to becoming a composer. This is NOT necessary if one is the conductor of a choral group. Musical detail is more important....balancing voices, bringing out the melodic line, tempo, dynamics and recognition of musical form. These are all musical aspects that are taught in choral conducting class, not theory class.