It Just Doesn't Feel Right

"So pay attention to how you hear.  To those who listen to my teaching, more understanding will be given.  But for those who are not listening, even what they think they understand will be taken away from them." - Luke 8:18

I came across this passage in my morning quiet time.  I usually do my quiet times before I even touch my computer, but today I turned it on early as soon as I read this.  I have read Luke before, but this verse has never really stuck out to me.  I wanted to get some input on what it means.


If we listen to the teachings of Jesus Christ, we will be given more understanding.  More understanding into God's mystery (if you look back at at Luke 8:10 it says "You are permitted to understand the secrets of the Kingdom of God".  Secrets literally means mystery - that's where I'm pulling this from).  That part makes sense to me. 


The next part is where I admit I'm confused.  "But for those who are not listening, even what they think they understand will be taken away from them."  Now when I read this the only logical conclusion is that they're not being let in on the mystery.  They don't get to know about the Kingdom of God and its mysteries.  When I think of someone who "thinks they understand" I think of a lukewarm Christian who thinks that knowing about Jesus and going to Church is it.   But when they pass on, they will realize that there was indeed more to be done. 


I don't think my interpretation of this passage is too far off, but I wanted some input.  The way I described the passage above just doesn't feel right. I don't know why, necessarily...it just doesn't sit well with me.  


So - am I right? Am I off? Can you add some crazy awesome knowledge?