Potential Bridemaid

I have a close guy friend that is getting engaged very soon and I`m concerned that his new finace will ask me to be in the bridal party. I`m not close to his fiance, in fact I wouldn`t choose to be friends with her if she wasn`t dating my close guy friend. Also, I don`t necessarily agree with this marriage, which neither one of them know that. Someone please tell me how to decline when asked by my friends fiance? I don`t want to hurt either however, I simply don`t want to be a bridemaid in this wedding.

Thanks in advance - Deb