What leads some enlightened to also reject consciousness and others to stay in spiritual ideas?
Because no one really wants to be enlightened, everyone wants to stay spiritual. The full truth of enlightenment hurts very much, in fact, it hurts so much that in full enlightenment nothing can hurt you any more.
Whereas it can be said that awakening is the beginning of spirituality, self-realization is the peak of spirituality, enlightenment is the end of spirituality.
It is the end of all hypocrisy, all lies. For as long as one wants to mire in his own hypocrisy, one will remain spiritual.
Consciousness also ultimately doesn’t exist. Consciousness is not you, it’s just an idea also. It’s a temporary identification, it is needed, but it must be transcended also.
The depth of the ancient teachings is underappreciated in modern times. The eyes cannot see themselves, they can only see their own reflection. Ego cannot see itself, and ultimately, consciousness cannot see itself also. If you’re still seeing consciousness, the evolution of your consciousness is not complete.
Show me you. Whatever you point at, it will not be you. You can point to your body, but if it’s “your” body, how can it be you? Everything you see, feel, touch, smell is not you. If you keep trying to find “you”, at some point you will understand that this is impossible, and your identity will switch to the whole, consciousness. But just like ego doesn’t exist simply because you can’t point your finger at it, the same can be said about consciousness, so it doesn’t exist also. Consciousness is what ego dissolves into, but when it is dissolved into it completely, it serves no purpose any more, so it disappears.
When asked to show himself, a person who realized Brahman will open his arms and say, “this, all of this is me”. Or he will say “I am That, which cannot be described”. A fully enlightened person who let go of Brahman would point to his body, and say “this is me, I am this body; whatever it’s seeing, hearing and touching is not me”.
Siddhartha Gautama understood this also. Two of the 10 fetters in Buddhism are lust for material existence and lust for immaterial existence. “I have a body” is an egoic mess. Who’s that “I” that has a body? By whom is it had? Show me that “I”. “I am consciousness/awareness/That” is still lust for immaterial existence, something ephemeral which exists outside of the physical realm and as such, can never die. Show me that also. The only statement which is undeniably true, and everyone of us knows it on some level is “I am this body, and this body will die”. There, now there’s no more clinging in you, no more hope to exist forever, materially or otherwise. Hurts? You bet. No more spirituality for you, no eternal life, no soul, no God, no exaltation, just the reality of your situation. But no more fear either, and no more emotional pain or suffering.
The truth is, we are nothing but biological machines, not in any way distinct from animals, and imagining that we are something more is just human vanity. Vanity is the nature of the ego. Which is why an enlightened person doesn’t see a difference between himself and a squirrel, and most people do. The benefit of realizing you are nothing but a flesh and blood animal is that, just like any other animal, if you are reasonably fed and warm, you are always happy, harmless and content, in the most absolute sense of the word. “Sticks and stones will break my bones, but words will never harm me”. Everything else, such as creative pursuits, goals, earning money, participation in society, socializing, good-looking furniture, raising children or serving humanity is entertainment. It can be tremendous fun, but it’s empty. Just an expression of the intellectual power of the brain, which was needed to survive before and is bored of sitting idly now, in the society where you can easily survive doing very little. This is the ultimate truth of your existence, not Atman, Brahman or consciousness.
Nothing that you cannot see, touch, smell, or sense actually exists. Your body exists, yes. The trees exist. Squirrels exist. Personality/ego does not exist, and consciousness doesn’t exist either.
Spiritual enlightenment is the process of accepting this truth, during which your identity/ego undergoes a series of transformations and relocations which I have roughly described here: Artem Boytsov’s answer to What is the ego?
Launch into it, don’t get stuck in it, be done with it, and move on with your life.