The man's abject actions made many people hate him.

Yes, it is a noun.

Tina Chanter has written:

'The Picture of Abjection' -- subject(s): Abjection in motion pictures, Sex in motion pictures

'Ethics of Eros'

Jill Adair McCaughan has written:

'Abjection and its correction in ethnographic studies'

Karen Shimakawa has written:

'National abjection' -- subject(s): Abjection in literature, American drama, Asian American authors, Asian Americans, Ethnic identity, Human Body, Orientalism, Performance art, Psychological aspects, Race identity, Race relations, Racism in literature, Social aspects of the Human body