WMG / The Devil is a Part-Timer!

The Church Destroyed Emilia's Village

"Conveniently," the village was destroyed by Lucifer mere days after Emilia was taken by the church, and this gave her a reason to fight. As soon as she heard, she immediately pledged to kill Satan. It could have been a False Flag Operation in order to motivate Emilia. The church proved itself corrupt and underhanded enough to do it, especially since everything rested in Emilia's hands.

• Alternatively, they didn't destroy it, but just let Lucifer do it in order to motivate her.
• Given that the angels are after Lailah, Emilia's mother, and her husband Nord, they also had ample motive to wipe the place out. And we find out later that they would have no compunction of doing such a thing. As of the current Light Novels, there's still no evidence of this but I don't think a False Flag Operation should be ruled out.
• Somewhat jossed and true: In light novels #8 and #9, Emi returns to Ente Isla to find her village still standing. Its in neglect from being abandoned but not in total ruins. The surrounding wheat fields are still intact albeit overgrown with weeds from neglect. Emi learns that when the demon army arrived in the area, a mere handful of demons entered the area of the village and most of the villagers simply fled before them, including her father, becoming refugees. On the other hand, the Church did tell the young Emi that her village had been utterly destroyed with her father and the villagers being killed. They did lie to her about what really happened to manipulate her. So, no False Flag Operation but the Church did lie to Emi about what really happened.

Chiho Imagination Theory

I know, I know, another imagination theory, but think about this. Nobody acts strange around these people who just showed up, and nobody else is even remotely aware of all of the cast's "quirks". BUT, my main evidence is the credits at the end of the episode. They all show Chiho alone, at different times. The very last scene shows her with all of the cast as dolls. She could be completely fantasizing everything, or they could all be real people who she imagines elaborate fantasies with to cure her boredom. She doesn't always seem to be in touch with reality... And in episode 13, she fantasized about Maou kissing her in his demon form until she was snapped back into reality by Maou... She could have just went right back to that fantasizing mindset after she was snapped out of it. Or, my personal theory, Chiho is dying. One of the things in the ending themesong that is shown is a pulse as Chiho silently listens to music. That was the second to last slide, before she appears with all the cast as dolls. She could be dying, and be in a coma and not doing any of the things she imagines. Her dying dreams could be her experiences with people she knew before she went into a coma. It would explain why she didn't appear in the last scene, she could have died by then and in the real world, the people who she imagined to be the "Devil" and the "Hero", Emi and Maou, were having a moment.

Emerelda Entuva is Ignora

Emeralda Entuva, Emi's close wizard friend is none other than Ignora, the Big Bad and Final Boss which the heros and demons will have to fight at the end of the story. Ignora is simply using her great powers to shield herself and take the form of Emeralda to spy on Ente Isla and the various factions. She wormed her way close to The Hero in order to keep an eye on her. When Ignora first turns up in Light Novel #10, she is in disguise, in an astronaut suit of all things. The figure is described as being very small in stature, like Urushihara. Emeralda is also very short. Entuva is also missing during this sequence although she conveniently appears out of a gate after Ignora is "driven off." Emeralda also wheedles her way into private discussions between Shiba and Maou's gang several times arguing that it is only to be helpful to Emi; the real reason being to find out what they are up to. At one point, she has a stare down with Miki Shiba in which Shiba comments how strong a will Emeralda has in a cryptic manor. So Miki-T probably knows Emeralda is really Ignora but is leaving that for Maou's Heroes to find out. Entuva also starts to act creepy from novels 11 on when Maou's gang learn that the only way to save Ente Isla is to destroy Ignora. In fact, she takes to abandoning her "job" in Ente Isla to stay on Earth full time, keeping close to Emi and Maou. Emerelda is also an incredibly powerful wizard, a good cover story for Ignora so that she could use some of her incredible power.

• There's also the fact that Alas Remus doesn't like Ignora at all. Supposedly because Emeralda scared her on their first encounter, Alas Remus never gets comfortable around her and avoids her at all costs. Even to the point of hiding behind perfect strangers from her. Who else do Alas Remus and her sister instinctively hate? The Angels of Ente Isla. Alas Remus may not know that Entuva is Ignora as her disguise is pretty good but there's still something there that makes the little girl not want to have anything to do with her.

Like Haruhi Suzumiya, Chiho is a Reality Warper

Light Novel #7 is a series of short stories. The last one features Chiho as a student long before she is involved with Maou and the rest. In fact, she meets him here and first applies for work at Mg Ronald. Maou is portrayed as a talented but quite ordinary young man who occasionally makes grandious remarks which could just be the result of regular Walter Mitty fantasies. Chiho is shown to be adrift herself at this point, not knowing what to do with her life or herself. She is also instantly attracted to Maou. When she gets home, she wonders if Maou has a girlfriend and what she could be like. In an eerie passage, she then describes each of her future friends:

Chiho put the schedule away with her notebook, turned out the light in her room, and went downstairs to talk things over. But the moment things went dark, a corner of her head was flooded with images of the imaginary life partner next to Maou: Some brave, gallant housewife, maybe, supporting his busy work schedule at home? Or maybe he got saddled with some lazy woman who wastes all his money? Or maybe someone who goes around in kimonos every day? Opposites attract, as they say, after all… Or maybe a woman who has it all together, working on her career just like Maou is?

While the people aren't Maou's girlfriends, these people are obviously Ashiya, Urushihara, Suzuno, and Emi. Before this moment, Maou Sadao was just a Freeter living alone or with family, eeking out a living working at Mg Ronalds. But at this moment, Chiho warped reality, turning Maou Sadao into The Devil King (perhaps from his silly fantasies mentioned at work and probably the result of RPG games). Her mind created all the backstory, the planet Ente Isla, the Angels (named strangely after Earth sources), and probably Miki-T and the Sephiroth. In this way, she also created a "purpose" for herself as she seems to be ending up being pretty central to saving Ente Isla in the latest novels.