"thought & extension (the only two that Spinoza ever refers to [thereby, inadvertently, positing a latent dualism]), is or can be conceived by “the intellect” as being identical with one another"
For Spinoza, conceiving attributes is kind of seeing aspects of the same drawing. You can see a duck or a rabbit, where in reality there is only a single drawing out there. The duck or rabbit are interpretations, they have no real existence. The simile is not perfect, though, because attributes are conceived as expressing the essence of substance, whereas the duck and rabbit are not essences. This also shows that their distinctness from each other and from the substance itself is illusory, for the substance cannot have more than one essence.

"God does not, can not, love us, but that we should love God."
This is because Spinoza's God is deeply narcissistic. "God loves himself with an infinite intellectual love." (Ethics 5, P36.)

All I've been trying to address is what is logically entailed by the idea. — Janus

No one can know what is logically entailed by that idea because no one can know if it is logically coherent in the first place. If it is not -perhaps because the idea of anything that is physical logically entails the presence of some energy - who can say with certainty that it doesn't just because he seems to be able to imagine it without energy? - then anything can be entailed by it because of the ex falso quodlibet rule.

I don't agree with you that idea of emergence in this context entails causality as we ordinarily understand it in an empirical context, — Janus

That is why I wrote that once you deprive emergence of causality, the remaining concept turns into a mystical one like that of emanation in the philosophy of Plotinus. Is this what you're claiming?

the quantum vacuum itself is spatio-temporal. — Janus

There is no such thing as "quantum vacuum" because there cannot be states with zero energy. You mistake the subject of a thought-experiment for reality.

this fact gives no ground for claiming that the entity from which the manifestations emerge must be spatio-temporal. — Janus

Quite contrary. this fact gives ample ground for claiming that the entity from which the manifestations emerge must be spatio-temporal. Your use of the word "emerge" is telling. You cannot say that these activities are caused, because ordinary causation is spatio-temporal. Instead, your choice of word "emerge" is close to "emanate", a verb with mystical overtones. There is absolutely no evidence for this kind of "emergence" or "emanation" (as distinct from causation) in our world. I seriously doubt that it is conceptually (logically) possible to have activities without actors, as their logical form must contain a placeholder for something that does the activity. And even if it is logically possible, it cannot be what Spinoza had in mind, because he says that water (or watering, waterly, etc.) IS substance under one aspect. So it does not "emerge" from substance, it IS substance itself, according to him.

The quantum vacuum is not thought to have "temporal parts" — Janus

Maybe you don't think it has, but it does nevertheless.
"According to present-day understanding of what is called the vacuum state or the quantum vacuum, it is "by no means a simple empty space".[1][2] According to quantum mechanics, the vacuum state is not truly empty but instead contains fleeting electromagnetic waves and particles that pop into and out of existence" https://en.wikipedia.org/wiki/Vacuum_state
So the quantum vacuum clearly have temporal parts insofar as it contains "fleeting" particles and particles "popping into and out of existence". These expressions refer to temporal intervals, no matter how tiny they are. And the vacuum is something that contains them, so, when conceived as an individual entity, it has temporal parts dated to these subatomic events.

And exactly what is your argument that something that has no parts cannot have activities — Janus

My argument is that the concept of activity presupposes an actor (or an undergoer background, if you claim that subatomic events are "activities") that must have temporal parts or temporal slices. This is because all activities start and stop at specific times and therefore they occupy temporal intervals during which a temporal slice of the actor exists.

Are you claiming that if something is thought to have no parts, that it must therefore be thought to have no activities? — Janus

Yes. Exactly. If something has activities, it necessarily has temporal parts. Activities are events and as such they take place in a specific period of time. So It will have temporal parts "filled" with different activities.

Is this your culture of argumentation? I'm sick of your ad hominem remarks. I have presented a number of arguments, while you are apparently unable to answer them, trying to cover up your incapability by putting yourself on a high horse.

NIce explanation, but irrelevant. Please give me an example of anything (X and Y) that satisfies 1), 2) and 3).

My affections are not a constitutive part of myself, they are activities, but they are real nonetheless. — Janus

the modes have an adverbial nature, rather than a substantival one - they expresses not “what” but “how” being is. — StreetlightX

So the substance is either "watering" (Janus) or "exists waterly" (StreetlightX). Apart from the blatant inconsistency of the two ways of expression (verbal or adverbial?), I wonder if you could support your interpretation by pointing to textual evidence where Spinoza says such fancy things.

"the cosmos" (i.e. Natura Naturata) exists (vide Einstein re: Spinoza) but only exists non-necessarily (i.e. contingently) — 180 Proof

No. All contingent existence is illusory. If you don't want to interpret Spinoza as contradicting himself, you must acknowledge this.

To see why, here is a challenge, an argument based on textual evidence. I use only three "premises", if you wish (although not in a strict logical form).

1) In Part I of Ethics, Spinoza explicitly asserts in its definition that a mode is "IN ANOTHER" ("By mode I understand the affections of a substance, or that which is in another through which it is also conceived.)

2) In the same definition, he also asserts that a mode is conceived through that "another" (so it depends on it notionally).

Thus, supposing that that "another" is substance (via its attributes), it means that all modes (if they
existed) 1. would be IN the substance 2. They would DEPEND on the substance notionally.

By notional dependence I mean that modes cannot be understood without understanding what the substance is (i.e. without understanding the attributes that form its essence).

3) BUT Spinoza must deny that modes inhere in the substance ("are in another") as parts in a whole. Why? Because, if they would, then substance would have parts. But Spinoza demonstrates that no substance can have finite parts. (Ethics, Part I, Prop XIII.)

Let me recap the main points: All Modes would be 1) "IN the substance", 2) would "DEPEND on the substance notionally" and yet they would 3) NOT be parts of the substance.

And here's the challenge: explain the following situation, preferably by giving an example of something (let us call it X) and another thing (let us call it Y) that meets all the three requirements below (of course, substituting "mode" for X and "substance" for Y would beg the question):

1) X is in Y.
2) X depends notionally on Y (X cannot be understood without reference to what Y is).
3) X is not a part of Y.

To me, this is sheer conceptual confusion. Yet, 1), 2) and 3) should be true of all finite modes if they existed. So you better admit that no finite modes exist, on pain of contradiction.

S makes the distinction sub specie aeternitatis between Natura Naturans (i.e. Substance) and Natura Naturata (i.e. Modes): the latter Non-Necessarily Exist - essences do not contain existence - and only are caused to exist only by the former which - its very essence contains existence - Necessarily Exists. — 180 Proof

Modes, according to Spinoza, are "God considered as affected". So it is all about "aspect-seeing", if you wish.
Let me return to the water example. Spinoza asserts several inconsistent propositions about water, each involving contradictory properties like "divisible-indivisible" "having separate parts - inseparable", "produced - not produced", "corrupted - incorruptible" and so on, according to the different aspects under which it is conceived - imagination (sense-perception) and intellectual intuition, respectively. To repeat, the very same water is seen as "a chunk of ordinary matter" (which is illusory) and "extended substance itself" (which is real). And it is very plausible to suppose that what Spinoza says about water must generalize to all physical entities, mass and count alike.
Unless you want to interpret him as someone who subscribed to dialetheism, you must resolve these contradictions. One property from the above opposing pairs must go - the question is, which one is to go? Clearly, the one that is conceived at a lower level of cognition, ie. sense-perception (imagination).

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Where does S state he is, as we seem to agree, an "acosmist" rather than a "pantheist — 180 Proof

Your comparison seems to me unfair. I requested textual evidence for his distinction between reality and existence - you gave none. My label "acosmist" is just my rephrasing a sentence quoted from Spinoza, in which he says that "measure to determine quantity" does not exist outside the imagination it is only an "aid to the imagination", which means that nothing - not even space - can be measured. Immeasurable space - that would be a real contradiction, wouldn't it? So does the cosmos as we know it exist in Spinoza's ontology?

all and any kinds of cognition and intellectual intuition would simply be emergent illusory phenomena like all the rest. — Janus

No. Intellectual intuition - the only non-illusory kind of cognition - can be said to be God's self-intuition. As you rightly pointed out, all the rest are illusory phenomena.

"The everyday world" (i.e. natura naturata) "is an illusion" only in the sense that it appears ontologically separate from, or independent of, the infinite and eternal Substance (i.e. natura naturans) to finite Modes like us — 180 Proof

I don't agree.The "everyday world" is substance itself perceived in a confused and inadequate way through the senses. But, for Spinoza, even reason is a partially deficient kind of cognition which "regards a number of things at once". The highest kind of cognition is intellectual intuition. Please re-read the passage on water. "water" is a mass noun, but what Spinoza says here must equally apply to all count nouns as well. Water (and anything else denoted by a noun) IS (extension or) substance itself when conceived ("intuited") properly through the intellect.

the perdurance of ephemeral surface waves relative to the long lasting ocean (i.e. Modes of Attributes relative to Substance) — 180 Proof

Several commentators want to interpret Spinoza as holding some "adjectival" theory of modes. I don't see how they can reconcile this with his statement that number (ie. plurality), time and measure only exist in the imagination - which implies that these are inadequate ideas, which Spinoza contrasts with the intellect's (adequate) conception of substance.

Please also note that Spinoza is a mereological nihilist as he demonstrates in Prop. XII. of Part I that a substance cannot be composed of parts. Therefore, if substance exists and cannot be composed of parts, no ordinary thing (mode) can be composed of parts either, because all modes are included in the attributes and attributes form the essence of substance. As the part-whole composition of ordinary things is illusory, it follows that they don't exist. QED.

Furthermore, please note that Spinoza writes about causation among finite modes, and the self-causation of the substance. Now, self-causation (causa sui) means that cause and effect coincide. Because in his system true causation is self-causation (this is what we have in our adequate idea of substance), it follows that all other types of causation are untrue, there is inadequacy in their ideas, and their relata do not exist. True causation means that the relata (cause and effect) are identical, which holds only of substance.

in the sense S conceives of the difference between existing and the real. — 180 Proof

Where does Spinoza make that distinction? Sorry, but I cannot find any textual evidence in support of the interpretation that he differentiates between existent and real things.

how does 'exist' imply that illusions do not exist? — Shamshir

Maybe illusion is not the right word. When I say illusions do not exist, what I have in mind are illusory objects, in effect hallucinations (oasis in the desert). They do not exist by the common usage of the word "illusion" which implies that they are not "out there".

If there is no space, where's the substance? — Shamshir

The question presupposes the existence of space, so it begs the question.

Ontological nihilism is the philosophical position that nothing exists. Spinoza comes very close to it. In its normal use, the meaning of the verb "exist" implies that illusions do not exist. Spinoza says that time, number and measure are merely "modes of thinking", but "modes of thinking" is in the plural, so illusions do not exist because otherwise a plurality of (illusory) entities would exist, which would imply the real existence of number (i.e. a plurality of things).
Let me add that for some reasons, Spinoza banishes all teleology and purposes from his ontology, so there could be no purpose of anything in it.
Space and time do not exist in Spinoza's ontology. Substance is aspatial and atemporal. Being infinite, it cannot have finite parts, and being indivisible, it cannot be measured.
For a different example, see his discussion of "water" in the Ethics (Part I, Note to Prop. XV).