Subaru dies a few encounters and learns a few things about the bishops, then takes the lead.
He uses the communication tower to reach out to the whole city, encouraging them that help is here.
He then splits up the team to combat the four bishops, and to put a stop to their destruction of the city.
On the cult side we have:
Sirius Romanée-Conti, Bishop of Wrath
Self-claimed wife of Betelgeuse. Covered in bandages ad dragging chains, she is overly excited maniac and when she senses her loved one inside Subaru, she first thinks her love had come back.
She has the ability to impose her emotions and her physical state with everyone around her, instantly forcing normal citizens to be empathetic to her and she uses this to brainwash and control them. They also take the same damage she receives, effectively turning them all into hostages.
This causes several deaths for Subaru, including times when he was driven mad from her influence.
Sirius is adept in combat, uses her chains and controls fire to fight.
She was eventually faced off by Priscilla and Liliana the bard. Liliana used her abilities to neutralize Sirius's empathy powers, and Priscilla defeated her with a flaming sword.
Capella Emerada Rugunika - Bishop of Lust
The worst Bishop of them all, according to the author.
She's neither insane nor have some zealous belief she hangs onto. Rather, she's purely evil and malicious.
She can transform herself and others to any form she desires, and loves to change people into something to make them suffer. She's also got dragon blood running in her veins, and uses that to poisons Subaru & Cruch.
Rai Baten Kaitos, Roy Alphard, and Louie Arneb - Bishops of Gluttony
There are at least three bishops of Gluttony, all with different personalities. They can "eat" a victim's name to erase them from everyone else's memory, or eat a victim's "memory" to make them amnesic. If a victim has his/her name and memory both eaten, they also become comatose. (that's what happened to Rem)
At one point they bring out Rem's personality using her memory, just to toy with their victims.
Julius, Otto, Ricardo, and I believe Betty faced them off, but failed to defeat or capture them.
Regulus Corneas, Bishop of Greed -
A very obnoxious and self-centered man who makes excuses for everything he does, while complaining about everyone else. He never shuts up, and is incredibly annoying. He has dozens of wives, forced to serve him in fear. They all loath him deep inside, but is powerless to stop him.
Enpowered with complete invincibility to any and all physical damage. His "Time Stop" ability allows him to freeze the time of his body and any object he touches, making it impossible to be destroyed. The only problem with this power is that it stops his heartbeat as well. He has another ability "Small King" that allows him to impose his heart on someone else, effectively "hiding" it, while burrowing that target's functional heart to keep him alive even when he freezes his own time.
Even Reinhart cannot harm Regulus , but Subaru finds out his powers and with the help of Emilia, manages to boot Regulus 's heart out. Reinhart curbstomps him afterwards.
With Regulus 's death, Subaru absorbs his witch factor.
On top of all this the Cult resurrected re-animated bodies of Teresia - the previous Sword Saint and wife of Wilhelm - and Gurgan the eight-armed warrior. Both Teresia and Gurgan are legendary warriors, and two of the strongest to ever lived. Of course Wilhelm faces off with his deceased wife, attempting to bring her back to rest. Garfiel went toe-to-toe with Gurgan, barely defeating him in a fierce and brutal combat.
In the end Regulus is killed and Sirius is captured, but Lust & all three Gluttony gets away.
Julius had his "name" eaten, and becomes forgotten by everyone but Subaru. Julius' younger brother Joshua had his name and memory eaten, and is in the same state as Rem now. Julius joins Subaru's team in arc 6.
Capella had turned her hostages into giant flies, and no one can find out a way to reverse this.
In order to prevent them from falling into despair and killing themselves, Emilia freezes the townspeople and swears to come back to help them once they find a cure.
The team heads off to the Tower of the Sage, one of the three beings who sealed Satella.
They seek the Sage out needing answers and guidance to many things, including how to cure Rem and other victims of Gluttony.