If you argue that all beings experience a Purgatory of sorts where they will eventually enter into Heaven, you're going to need to say why you are denying that there is Hell at all. Clearly that argument would be
a universalist position. Sider's argument concludes that we should not view the afterlife as binary. But he does not claim that there is no heaven or hell. Perhaps, because you favor Sider's conclusion, you might ascribe to a universalist argument that goes like this:

1. If hell exists, then there is a distinct boundary between heaven and hell.
2. If there is a distinct boundary between heaven and hell, then God decides that similar people will receive radically different afterlife sentences.
3. If God decides that similar people will receive radically different afterlife sentences, then God will not be perfectly just.
4. If hell exists, then God will not be perfectly just.
5. But God must be perfectly just.
6. So hell does not exist.

It seems that if hell exists, then there must be a solid boundary between it and heaven or purgatory. This is because if there were no boundary separating hell from heaven or purgatory, then hell would just be just like purgatory, or an extension of it. In other words, something like eternal damnation is not on a spectrum of shades of gray, but a solid division. The problem, however, is that this argument could be applied to heaven. That is, something like eternal salvation is not on a spectrum of shades of gray, but a solid division. Clearly, an argument like the one above is not sufficient for denying the existence of hell. But if, as you claim, there is purgatory where all beings eventually enter into heaven, then we need to say why there is a heaven but no hell. It would have to follow, then, that all beings are placed on the spectrum of purgatory depending on how they lived their earthly lives, eventually passing some threshold into heaven. But if a threshold like this exists for heaven, why can't it exist for hell? Perhaps God never sentences anyone to eternal damnation (hell) for some reason, and, from their spots in purgatory, they can only move up the spectrum toward heaven. But why would hell exist if nobody ever gets sent there by God? It would seem that you still need an argument denying the existence of hell, and one that is better than the one laid out above. Clearly, Sider's work concluding that we should not view the afterlife as binary does not work for denying hell. But it would be important for you to address why you agree with his conclusion, yet see the afterlife as having two distinctions: purgatory and heaven.

Your argument seems to go, as follows, like a usual design argument:
1. If the universe has all the trappings of design, then the universe must have a designer.
2. The universe has all the trappings of design.
3. Therefore, the universe must have a designer.

As you mention, people object to this argument by objecting to (1) by saying that the order of the universe could arise randomly without a designer. You argue, using the two rooms experiment, that this is a bad objection because people see ordered things on earth and conclude that there is a designer/occupant, yet reject a designer for the universe which too is well-ordered.

I would argue that your experiment is disanalogous to the design arguments for the universe. Clearly, both rooms have at least a touch of design; they have items in the room that got there somehow. Room A is in disarray, but not by chance. At least one being put those items in the room, whether they were placed orderly or not. Also, as one who has seen a college dorm, it is not unjustified to conclude that the room in disarray is the occupied one. There are reasons to believe that an occupant’s intentions are to be disorderly. Perhaps the room started out orderly, then a person over time made it disorderly. Clearly, if both rooms started out orderly and only one ended up disorderly, the disordered one is the one with the occupant. This is in opposition to what you said about the two room experiment. Perhaps, in the same way, the universe could have been disorderly even with a designer. Maybe one would object that purposeful disorder is still, in fact, a design. But nonetheless, it still seems possible that disorder could arise with a designer.

Additionally, a room is like an artifact, which is intentionally made by humans, rather than something like the ocean or the mountains. But the universe is not like an artifact. Humans make justified assumptions about things like artifacts because we know how they work. But humans often make unjustified assumptions about things that are not like artifacts, such as experiences.

This is going to be pretty out there. I attempted to put your argument into a formal argument form but it was pretty tough. Hopefully this is close.

1. Eventually, technology could get so advanced on earth that it might be possible for there to be some technology powerful enough to be considered the technological god.
2. The technological god could not come about without corporeal beings creating it.
3. If humans are the only corporeal beings on earth potentially capable of creating the technological god, then human purpose is to create the technological god.
4. Humans are the only corporeal beings on earth that are potentially capable of creating the technological god.
5. Therefore, human purpose is to create the technological god.

Regarding premise (1), it seems plausible that technology could become so advanced as to be more powerful than humans. But the less plausible part is being able to call that technology the technological god. What would a technological god be? At the very least it should probably be omniscient and/or omnipotent. How would technology do that? How can it gather every single piece of info about every single thing on earth or about the world while it is existing within it? How can it make predictions about a constantly changing world? Perhaps it is possible, I’ll grant. But it seems hard to see how a technology that was created, that has a starting point, be omniscient because it cannot know everything that happened before it was created. No amount of recorded history, biology, chemistry, or physics could give the technology more than humans know about any other those subjects. Humans cannot give it more knowledge or information about the past than they know. Perhaps someone could just object that an all-powerful, omniscient technological god could be created, it is difficult to think about the technology that would be involved in that situation because we do not have that technology or knowledge right now.

Regarding premise (2), I think it sounds good if the assumption is that the technological god is corporeal. Maybe, if the incorporeal God exists, He could summon it down to earth or something like that. But if so, that would defeat the purpose of the question being asked: whether or not it is human purpose to create the technological God. So it’s probably better to assume that God doesn’t intervene like that, and some corporeal being(s) on earth create it.

Regarding premise (3), the conditional seems wrong. It seems to falsely equivocate purpose and capability. It doesn’t explain what the connection is between the two. Humans are capable of lots of things that are not, or do not seem to be, their purpose (e.g. eating, going to the bathroom, killing people).

Regarding premise (4), only as far as we know, humans are the only corporeal beings on earth that are potentially capable of creating the technological god. Even then, it could be argued that humans are not actually capable of doing so. But either way, this premise is questionable enough, especially combined with the objections to the other premises.

Overall the argument seems really weak.

It looks like your argument goes as follows:
1. If we have free will, then we have the free choice to do good or to do bad.
2. We do not have the free choice to do good or to do bad.
3. Therefore, we do not have freewill.

Premise 2 is obviously the one to question. You believe God “rigged” the system because God rewards the good more than adequately but he hardly punishes the bad as much as he should. You believe the heaven-hell incentive scheme makes the option of doing good and avoiding the bad an option that cannot be refused because heaven is so good and hell is so bad.

I do not think that supports the claim that we do not have free will. Firstly, it seems that if eternal joy in heaven really was an offer no one can refuse, then nobody would choose to do bad. But, clearly we see people choosing to do bad all the time. This is not the strongest objection, but it is something to consider nonetheless. It seems that the only way for heaven to be an offer we cannot refuse is if God exists. If one does not believe that God exists, then the offer of heaven does not seem nearly as appealing, if it all, and the threat of hell would not seem as formidable, if at all.

But even if it is granted that God exists, there is at least one problem with saying that we do not have free will. If we lacked the ability to choose between doing good and doing bad, then our characters don’t have moral significance; we would simply act the way we’re programmed to act. We would not be praiseworthy, or earn our way into heaven, for doing good if we did not have the free choice to do so. In other words, the option of heaven seems to go away entirely if we say we do not have the free choice to do good or bad. That is why it is important that we have characters that have moral significance. Thus, premise 2 seems to be false and we could be able to claim that we have (and need) free will if God exists.

Here is a basic argument for the claim that miraculous events are evidence for the divine:

1. If a miraculous event happened, then the laws of nature were violated.
2. If the laws of nature were violated, then God made it possible.
3. Therefore, if a miraculous event happened, then God made it possible.

Premise (1) seems true, as long as the agreed upon definition of ‘miracle’ is a violation of the laws of nature. It seems like that is the way to go for defining miracles, so I’ll leave this premise.

Premise (2) is the more problematic one. One could object that God need not be posited to explain violations of the laws of nature. For instance, the only reason we have to believe that there are unbreakable laws of nature in the first place is because we have never, in the past, seen otherwise. But it does not follow from this that future events must follow the laws of nature. Just because we have always seen things follow the laws of nature in the past does not mean that things will always continue to do so. We have no grounds at all to say that the future will behave like the past, we can only say it probably will behave like the past. And it seems hard for someone to give reasons that miracles are evidence for God’s existence. It doesn’t seem to work to argue this way. The reason is that you would be using evidence for God as background evidence then using miracles as posterior evidence. It wouldn’t be the other way around. I think, as I will explain below, it would be best to go the other direction.

You are asking for an argument denying that miraculous events are evidence for the divine. I think the objection to premise (2) in the paragraph above supports that aim. Further, it seems more correct to go in the other direction. Perhaps we need really solid evidence for God’s existence first, so we can argue from that to the possibility of miracles. Arguing from miracles to God seems less plausible than arguing from God to miracles. For instance, the concept of God, specifically his maximal power, would allow him to uphold and violate laws of nature at his will. It wouldn’t be that the possibility of violations of laws of nature prove God exists. In this way, God could be used as evidence for miraculous events. But miraculous events cannot be used as evidence for God.

It would go something like:

1. If God exists, then He would be maximally powerful.
2. If God is maximally powerful, then He can violate the laws of nature at will.
3. If God can violate the laws of nature at will, then miracles are possible.
4. Therefore, if God exists, then miracles are possible.

It looks like you laid your argument out as follows:

1. If humans were not aware of the presence of any gods or God before their respective religions came about, then these gods or God could not have existed before their respective religions came about.
2. Humans were not aware of the presence of any gods or God before their respective religions came about.
3.Therefore, any gods or God could not have existed before their respective religions came about.

For simplicity, I’ll speak in terms of God for now. Objecting to the conditional in (1), God could exist before any human defines Him. This is sensible because humans make things, so one might suppose that humans and the world were made by something--perhaps God. A creation must necessarily come to exist after its creator. So if God created humans, then humans came after God. It follows that humans’, and humans’ definitions of God, came after God.

God might be described as transcendent, omnipresent, and/or omnipotent. This would allow Him to transcend our concepts of time and space. However, it does not even seem that (1) is compatible with that description of God because it traces God’s existence to the instance that humans became aware of Him. Yet it does not seem like you are arguing that we need to revise our descriptions of God. It seems that you are arguing that because God is transcendent, omnipresent, and/or omnipotent, we cannot observe His existence. Further, because His existence cannot be observed, religions made up their concepts of God. So you, the author of the original post, may want to conclude that we should not ascribe to any religion that makes up concepts of gods or God out of thin air. But, it would be replied, religions do not make up concepts of gods or God out of thin air.

Regarding (2), this is not the most unsensible premise. My biggest issue with (2) is not the premise itself, but that you are so adamant to say that it is absolutely, without any doubt whatsoever true. It seems there is at least some reason to doubt it. Humans, before religions, might have speculated that something such as God existed, but did not have available to them the religious language used now. Even now, children can be aware of something ‘out there’ such as God without exactly knowing what/who God is or what to call Him, and can do so without having been introduced to any religion. To be charitable, I would grant this premise because objections to premise (1) do all of the work needed.