"Antigen is a substance that causes 'antiness'."
"They always in the side of 'antiness'."
I'm looking for a word (noun) that means 'state of being anti' (anti=against) for something, something like 'antiness' or 'againstness' (if something like that would exist... I mean, these two words don't really exist but they absolutely can give an hint for what I'm looking for.)
Editing: the word againstness exists in English. My mistake. (thanks to Malik)