If you really want the answer as to why keeping a "cold shabbat" is technically the proper way to keep shabbat, here is the answer. I feel fairly qualified to explain this matter and the misconceptions you seem to have about it. From the halachic standpoint anyways... Seeing as I do study on yeshiva and have an entire library in the next room on the subject matter, lol.
I think you're at a misconception of what "rest" and "work" means as it's defined by oral law/Torah. The idea of "work" is defined as work in which you are doing a process which changes the infrastructure of the physical world as it's defined by Halacha. The word used for work is מלחא(melacha, I think that's how it's spelled?) - as opposed to אבודה(the word ALWAYS used for work except in reference to shabbat). It's more so, if you look at it - creative works. Works that involve a creative process.*
There are 39 melachot which we are forbidden to do according to the Talmud. It's in mishna shabbos. If you want a complete list, it's do a google on mishna shabbat 73a( try mishnah shabbos 73a if you can't find it).*Here's an example from the Gemara I'm learning. However, they're effectively derived from the types of work listed in the building of the temple/tabernacle. Those types of work are forbidden, where as say... Moving a table wouldn't be since it was never part of what was considered work in the building on the mishkan(tabernacle).
You can cut open a barrel of wine on shabbat but you can't tear a shirt - it says this is Makkos, in the Gemara for the 3rd mishna somewhere on the bottom of the second page (can't remember what page it is specifically). Now, why is this? Because the way a barrel (in those days at least) is made is by multiple slabs and bound together by metal bands and serves a vessel for carrying wine. When you cut open the barrel, it effectively renders it just a cut open barrel. Same thing as opening a soda... With a sword >
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However, this works on different levels as opposed to why tearing the shirt does not. Such as... It has not been bonded in the same way the garment was made, since the garment is effectively one thing and tha garment being referred to was the garment for the tzitzit. Which is a 4 corner garment made entirely of wool or just one material(cotton is also acceptable) - though this prohibition carries over to all garments. Where as the barrel functions as one unit to serve one purpose, which is storing a liquid, and is bonded together with mutiple slabs of wood and bands of metal and functions on pressure from gas from *the fermented wine inside.
Effectively, since the barrel works from multiple objects, when you cut it open you're not changing its use as a single vessel, only opening it up. Where as the garment which has been torn now can be used as a different vessel, seeing as it is made of one material(fabric of some sort). Effectively, in the one case of tearing the shirt, you're breaking something that was bonded and has the ability to now serve a different function. Which in the case of the tzitzit, would be having a wider neck opening. Therefor, it is indeed an object that was bonded together for one purpose, which is being broken and can now be used for a different purpose. Where as the wine barrel which functions in a different manner of bonding being cut open does not pose a problem since it has been effectively opened up and still isthe same vessel which still is meant for the same purpose.
See what I'm saying? In one instance you're altering something which is considered a sigular vessel made of one material, the other since it is not one material it is not an issue to destroy since it's not been bonded in the way which it would be considered merged.
Therefor, to illustrate one is an act which changes the fundamental nature of it's being - the other is not. That's what true rest in the spiritual sense is and it is encompassd in a the 39 melachot which were used to build the temple. When the temple(or tabernacle) was built, it effectively epitomized the nature of holiness in the physical world. The 39 works which were done in this building of the holy temple emphasized the truly deep philosophical implications of what work is because the types of labor done to build the temple, were philosophically speaking every possible type of change which can be physically done in this world.*
Therefor, the reasons which seemingly simple and effortless works which sometimes make life easier, such as driving and turning on a light, are forbidden - is because they philosophically are changing the nature of what is at hand. That is work. Work changes things. To rest means to abstain from changing the world - not necessarily sitting on your *** and having a day off from your job. Because a job is not always work. If you think that this is what rest is in the case of the Torah, then, certainly if someone asked me to stay at their house over shabbat and watch over it - then would this be forbidden? Because that would by your understanding of work, per force would be forbidden.
A simple answer to some of the other halachic issues on this thread: you can have hot food on shabbat. Only if it's heat source is put on before shabbat. Thus crockpots are a common thing, ever have chollant?
Locks are not forbidden. However, electric locks are as using electricity violates multiple prohibitions in most cases.*
One of which is applicable in some cases, kindling fire. How? Electricity comes from generators - most electricity comes from generators which indeed kindle fire.
Another reason would be building. Turning on the electrical appliance completes an electrical circuit which is fundamentally the same as building. The same would carry over for an electrical keypad lock since you're completing a circuit. Fundamentally, this is akin to building.
This also in the same breath falls under the rabbinic prohibition of creating. Though all prohibited acts share the same common factor, creating, it was created as an additional prohibition by the rabbis. It becomes another issue in ADDITION to building when you operate anything electrical, particularly when you activate an electrical circuit. Because not only did you do the act of building, but you also, as a RESULT OF BUILDING created a brand new circuit which is very serious. Since it can be used to operate various electronic appliances and is something new.
Keys and locks otherwise are definitely not forbidden. However, all laws of shabbat become nullified to save a life
Sorry if I'm sounding like a know it all, but this is ultimately what the bare logic comes down to. That's the beauty of Torah and G-d and shabbat. It's understanding is concealed. It is a Jews duty to reveal it.
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