"We do," the human theologian says, "they happened after humans rebelled against God."

"That seems a little extreme, we have treaties against bioweapons on Amenta - I suppose that's neither here nor there, I'll leave treaties with God about bioweapons to the blues. So, we have infectious diseases too, and we don't want to catch them. We quarantine sick people, we require everyone to be vaccinated against anything they might otherwise get, we have an international holiday about the invention of plastic and another one about glass because they're so useful in keeping things clean. We don't like bugs or mold even though those things aren't strictly themselves infectious diseases, because bugs can carry it and mold can be poisonous in a way that mimics disease. But that's all the biological underpinning. There are some things that are dirty, are a bad idea to handle, are repulsive, even if we can verify with advanced instruments that there is nothing poisonous or infectious on a specific instance."

"Pollution makes sense," the SF writer says agreeably, "as a thing for an evolved species to have. Probably we don't have it because God created us as-is, instead of using evolution as His tool."

"Infectious diseases are not a bioweapon," the human theologian says, "it's sort of... the natural outcome of the Fall of Man. It twisted the whole universe: it created predators and parasites and diseases and all manner of evil things." He does not seem inclined to offer an opinion on the validity of pollution.

"...we have predators and parasites too. I'm not sure how a rebellion could cause that. Do you want to elaborate on that now or should I go into more detail on pollution?"

"Probably best to finish the explanation of pollution first, then we can talk about theodicy," the SF writer says.

"That's not translating," says the green. "I'll be interested to learn what it is. Anyway, some things are polluted. The primary pollutants are: waste from people - that's defined formally as substances the body actively rejects, which is in our case - you might be different - vomit, urine, pus, and feces, and the products of coughing and sneezing in a sick person, but not blood, tears, sweat, saliva, healthy people's mucus, hair that happens to fall out, shed skin cells - those all leave the body for other reasons. Historical cultures have considered some of those things polluted but as we've learned more we've concluded that they aren't. Another primary pollutant is corpses. You can tell a story about this originally having to do with people who died of disease still being contagious, but it applies even if they died for other reasons, like accident or an allergy attack - the body is still polluted. And there's reds. Reds are Amentans, and red is an Amentan caste, but the red jobs are ones that involve dealing specifically with pollution. Plumbing, corpsetaking, we also have them take away ordinary nonbiohazardous garbage but in principle purples could do that. Over enough generations of this, the pollution became ineradicable from the reds themselves. They're conceived polluted, born polluted, polluted all their lives, and can't wash it off in the shower the way other people can. So jobs having to do with reds that don't strictly have to be done by clean people are also the province of reds."

"That sounds awful!" the SF writer says. "I assume you give them lots of money or honor or social status or something to make up for having to be polluted forever?"

"They do get paid for their work, but it would be very difficult to give them honor or social status considering that nobody wants to think about them," says the green. "They're certainly very important."

"That sounds like a problem," the SF writer says sympathetically. "Maybe since we don't have a pollution sense we can talk to your reds? We've probably going to want to send missionaries-- those are people who teach other people about God-- anyway."

"Well, I don't think that's going to get any traction until you demonstrate that you understand pollution. It's a really serious problem, and if someone who was confused wandered into a red district and didn't decontaminate - I don't know how the extradition will shake out, you understand, but pollution crimes go all the way up to capital."

"We believe in respecting other people's beliefs," the SF writer assures the green, "and we would definitely never send a missionary who was going to commit capital crimes."

"I still don't think talking to reds is a great idea. What are the missionaries for?"

The human theologian takes this one. "When God created the world, everything was good. Then humans rebelled against God and sin and death entered the world. To save us from sin and death, God became a person named Jesus. Jesus lived for 33 years and taught us how we should live, then he died on a cross for our sins. Three days later, He rose from the dead. Now, you can be freed from sin if you accept Jesus into your heart as your personal savior. If you do, you will get eternal life in Heaven, while if you don't you will suffer eternal torment in Hell. We want to spread the good news of salvation to everyone so that everyone can rejoice with us in Heaven."

The green theologian looks completely blank at this. "I understood some of those sentences," she says.

"Can you say the first thing you were confused by?" the theologian says.

"So, if everything was good... and humans rebelling against God was bad, which seems implied... why did a bad thing happen when everything was good?"

"God gave human beings free will, which meant that even when everything was good we could still choose to commit sins," the theologian says.

"All right, but why did they do that?"

"They were tempted to sin by Satan."

"Who's that and why weren't they also good? Also 'sin' seems to carry more weight for you than is translating."

"Satan used to be one of God's angels. He decided that he wanted to be ruler of all creation instead of God, so he rebelled against God. He was cast out of Heaven and now he tries to do everything he can to keep humans from God. Sin is a thought or action that falls short of God's will. The wages of sin is death."

"- are you telling me you people drop dead if you think something he tells you not to?"

The human theologian is not sure how to untangle the confusion here. "No, death entered the world when humans sinned for the first time. We all deserve death because we are all sinners. But due to God's free gift of grace we can all have eternal life at His right hand."

The green turns to the sci-fi author. "Help me out here," she says.

"Sin doesn't make you literally physically die," the SF writer says. "It's a sort of... metaphorical and spiritual thing. You separate from God, who is the source of all good in the world, and that means your life is empty and doesn't have good things in it. If you accept God's forgiveness, then you can be close to him again. Also, after you literally physically die, you can either go to Heaven or Hell. Heaven is eternal closeness to God, while Hell is eternal separation from God. If you've committed sins and haven't accepted God's forgiveness for them, then you will go to Hell."