BEWARE OF SPOILERS.
Season 1
1 - Psalm 46:5- The Tarasks. Demonic, minotaur-looking entities that hunt the Warrior Nun. The ending of the episode shows one tearing Shannon's back to shreds while searching for the Halo.
4 - Ecclesiasticus 26:9-10
- Sister Frances makes for a chilling piece of Realism-Induced Horror. A malicious nurse who kills orphans she feels amount to nothing, in particular treating Ava with nothing but contempt and derision until she finally kills her with a lethal injection. She's pretty much a less-blatant version of Annie Wilkes.
- Ava stumbles upon her in the orphanage about to kill a young boy Ava was friends with.
5 - Matthew 7:13
- Lilith getting impaled and dragged into Hell by a Tarask. It's an utterly horrifying sight to watch as she disappears into a pit of fire and brimstone.
Season 2
1 - Galatians 6:4-5- While Lilith killing the FBC guards is a kickass moment, it's also terrifying as we watch her tear them to shreds before killing them brutally, in contrast to her fairly simple throat slit of Sister Crimson. A sign that Lilith has changed for the worse since Season 1.