The core issues at play (God & Satan / Good & Evil) can be & should be tremendously compelling (as demonstrated through thousands of works of art/music/literature/film). End of Days, unfortunately, is nothing but a 2Dimensional Cartoon. Byrne's acting ability stands so obviously in sharp contrast to Arnold's corresponding lack of ability and is further underlined by a plot filled with nothing but stereotypes.
The single compelling scene occurs at the very beginning with the transformation of the Gabriel Byrne character and his subsequent interaction with his wife? girlfriend? It is both erotically charged & repellent -- modernizing the vampirish themes, the seductive power of evil.