There's a difference in how you approach people is all it boils down to. People that come to my door with their inspirational messages? Well let's just say the family now tries to beat me to the door so I don't have to tell them what I really think. You want to live your life according to your beliefs and are a good example and in such share with me favorite passages or sayings or stuff you learned great! (I still think it should be illegal to pimp out children door to door for your religion, but I digress)
You are poly, you want your partner to accept this, nothing new there. Can not COUNT how many intros I have seen here and on lists that boil down to, "How do I get my partner to LET ME be poly?"
Here's the thing, trying to prove it's fine, it's acceptable, or even it's superior and more natural is NOT the way to go. It's condescending and is just going to put backs up! Instead, try saying, "Hey, I know this isn't for you, I know you dont' want any part of this but the truth is poly is who I AM, even if it's not what I do. So I read this book, and it really helped me put things into perspective. If you would like to read it I think it would do a better job explaining how I feel than I seem to be able to. Totally up to you and if you want we can even read it together and I want you to ask questions. I don't want this to be some scary unknown for you. So no matter what decision we make for our relationship, this could help you understand me better."
Wordy yes but a much better approach.