If you learned some music theory and/or harmony in school back in the days, did you enjoy it?
Was it practicable, applicable to a real life of musician's profession?
Were you inspired by your skills to apply them to the pieces you were studying at the time?
Or better yet, did your newly gained knowledge propel you to create something of your own, instead of just analyzing pieces of others?
Or was it some artificial system designed to flunk students as much as possible?
These are crucial questions to answer, if you want to befriend music theory and harmony now, later in life, when your mind is mature, when you're no longer required to do what you're told.
And you need it, if you want to be a more complete organist.