Consciousness is not a phenomenon. Consciousness belongs to an entirely different category.

You're going to have to provide some evidence for that assertion.

Another way to see that consciousness is not a phenomenon is this: If consciousness were a phenomenon there would be objective ways to find out whether consciousness is present in a physical system or not. But this appears to be impossible.

Well, I'm a physical system, and I have conciousness. Other people are physical systems and I can detect conciousness in them.

After all it's possible to conceive of a system that has intelligence but not consciousness, or else consciousness but not intelligence.

Is it? Can you give an example, please?

Trivially, according to the argument from consciousness, if God did not exist then consciousness wouldn't exist,[...]

You're going to have to demonstrate that, because I don't (yet) accept the argument. It sounds, as you say, very much like question-begging to me (and that conclusion is not dependent on my atheism).

If God exists then our experiential environment should be optimized for us becoming better people

Ditto - I need you to show the chain of reasoning from the premise to the conclusion, there.

If God exists then we should continue to have conscious experience beyond physical death. It's true that one can only make this observation only in death - but this is nevertheless a valid observation that if confirmed makes the existence of God more probable.

But it's the "if confirmed" that's problematic, isn't it?

So many people commit the double logical mistake to assume that as science is so successful in explaining physical phenomena it will be able to explain everything,

And they would be wrong

and to assume that as religion contains so many wrong beliefs all religious beliefs must be wrong.

And they would be wrong. So what? The "intelligence correlation" argument is not one that I care to use, for two reasons - the difficulty in defining intelligence and the simple fact that correlation is not the same as causation.

According to all that science teaches us we would expect that the universe should be swarmed with intelligent civilizations aggressively expanding.

Does it? I've seen plenty of scientific arguments to explain why we don't see that.

But the universe is dead silent. How can we explain that observation? There are several possible answers but I find them all highly unlikely (life is an incredible rare phenomenon; we happen to be one of the very first civilizations in the universe; we exist in some kind of protected cosmic zoo; all civilizations self-destruct; we live in a computer simulation.) By far the most probable explanation

Most probable? By what measure?

is that the universe is quiet because all civilizations (that do not self-destruct) evolve towards a spiritual and therefore humble kind of organization - evidencing that intelligence slowly but surely leads towards theism.

There is absolutely no evidence whatsoever for that assertion.