First Erosa I can understand your waryiness. I think that you will start to find more and more christians that are normal and poly. I have actually met 2 couples that come from an evangelical christian background and are poly. One couple is both female. The other had been married for 1l years and then became poly. It is funny when you study the history of monogamy and find that it is a new inventiopn that really didnt take hold till around 1100. But before that there was a patriarichal aspect that erosa was warninbg against. Some of the books that really he;ped me to awaken were "The poisoning of Eros" by Raymond Lawrence. Divine Sex: Liberating Sex from religious tradition by Philo Thelos. Erosa I would recommend you check out this site to help you understand where I am coming from.
http://www.libchrist.com/index.html