Viper (previously known as Madame Hydra) is a major super-villain in the Marvel Universe. She has been a frequent opponent of Captain America, the Avengers and the X-Men, among other heroes.
Viper's religion is nihilism. She has stated that she is utterly devoted to nihilism. This is demonstrated very vividly in Captain America #180, the issue in which Madame Hydra first adopts her new nom de guerre: Viper.