Hi Dante,
I've made some editing suggestions (Standard American English) and comments on content. The requests for more detail just mean I want a word or phrase. I'd be less concerned with length and more concerned with whether or not you can stick it somewhere on the website. It has promise.
[Edits]
“Please, God, let me do horrors unto this world . . . Please, God, let me do horrors unto this world . . . Please, God, let me do horrors unto this world . . .”
[I added this because he was chanting.]
That’s what that son of a bitch said to me from across the interrogation table. He kept his chanting going while I just stared into his upward facing eyes, trying to get a read on what he’s thinking. [This would be a good time to describe him. Does he look weird or normal?]
“So, you admit to the murders?” I [asked] quizzically.
He looked down from his star ward [I’d hyphenate “star-ward” since it is not technically a word in the dictionary, but that’s just me. It’s up to you] gaze and met my eyes.
“I never contested that I murdered. I only ask that I may commit more atrocities.”
I laughed. [Who is the narrator? I assume he’s an investigator.]
“Well, I doubt God would help you with that.”
He returned to his upward gaze.
“Please, God, Let me do –”
I left the room when he said that, I didn’t need anything more from him, and if I did need something I doubt he would comply. [You’re not supposed to contract “had,” but people do this when speaking. However, there were too many “had”s contracted here, so I edited it a little.]
Officers, detectives, and fellow interrogators met me as I walked out of the interrogation room exit [You were missing the preposition “of].
“Well, it’s an open and close case. We have a confession and we caught him red handed.” [Is Mendoza saying this?”]
Everyone around me nodded.
“Well,” Detective Mendoza said. “Looks like we won't be working late this week. Good jo—” [No dash after well, even if he pauses briefly.]
Mendoza stopped and his hands covered his eyes. “Mendoza, what’s the problem?” [Just put a question mark. I think the next sentence causes us to assume there’s a break in conversation.]
He started to hit the wall beside him.
“My head.” Mendoza grunted.
The police officer beside the pained man fell beside him. [Okay. I’m confused here. Who fell?]
“Hey, get some ice and some Sudafed. He’s having one hell of a migraine.”
The man to my left [Can the men have last names? It would help readers quickly identify them.] complied and left the room to go find some drugs [Ahem. He found “medicine.”]. “Hey, stay calm!” the officer asserted. “You’ll be okay.” [I know this looks strange, but you will not capitalize the word “the”]
Mendoza began to convulse, and soon after was thrashing violently. It was so bad that the officer by his side left him [Do you mean he left him completely, or that he had to step back?]. The detective screamed and looked to [appeared to] be fighting the pain in his head. Mendoza threw his head up [He yanked or raised his head. When you say “threw up his head,” I can interpret that as “Vomited his head up.”], revealing his bleeding eyes with a booming scream [Make it clear that his eyes are not the thing screaming. He’s screaming], [sounding] much louder than his human [He’s still human, I think, so you might consider saying “normal” instead. Is he still human? I think you mean he’s a human making an unnatural scream] screech before. The screaming continued [which brought everyone] in the room to our knees, save for Mendoza, who walked spastically [I’m not sure he’s “walking.” Wouldn’t he be “lumbering” or lurching?] to the interrogation room door. When [Mendoza] reached the door[,] [his] cries reached a crescendo[,] and he became fully engulfed in light. [In t]he next second[,] there was a hole in the wall, and a figure emerged from the artificial exit. It was that murdering fuck walking out, cloaked in bright, white light. The last thing he said to me was: “Please God. Let me do horrors unto this world.”
Content comments: I think you are trying to say that people do terrible things in the name of Christianity and/or, but I have to do a lot of work to get to this claim. Some people might never get it at all. The man talks to “God,” but there are a vast number of these. I know this might be the point, but it is just too vague. His God could be a demon he calls God. Who knows?
It might be better to describe him as looking like a holy man. He could have a beard or wear a robe. I think this would be okay.
I don’t think it needs to be a micropasta.