There is only one truth in absolute sense. It is Allah Himself. In various parts of Qur'an, it is ordered that Allah (swt) is the only truth:
"That is because Allah is the Truth." (Luqman, 30)
"All that is on earth will perish: But will abide (for ever) the Face of thy Lord,- full of Majesty, Bounty and Honor." (Rahman, 26-27)
"That is because Allah - He is the Reality; and those besides Him whom they invoke,- they are but vain Falsehood: verily Allah is He, Most High, Most Great." (Hajj, 62)
"On that Day Allah will pay them back (all) their just dues, and they will realize that Allah is the (very) Truth, that makes all things manifest." (Nur, 25)
"and that Allah is well-acquainted with all that ye do? That is because Allah is the Truth, and because whatever else they invoke besides Him is Falsehood; and because Allah,- He is the Most High, Most Great." (Luqman, 29-30)
"Soon will We show them Our Signs in the (furthest) regions (of the earth), and in their own souls, until it becomes manifest to them that this is the Truth. Is it not enough that thy Lord doth witness all things?" (Fussilat, 53)
# Created realities
"Physical world" and "Spiritual world" are created realities. Their existence and survival are possible with the will of Allah (swt) because their existence, layouts, energies, and operation mechanisms are given by Allah (swt). A bird cannot flutter, a baby cannot breast-feed, or a leaf cannot photosynthesize if Allah (swt) does not want because Allah (swt) creates and programs them to perform the activities and bestows them with the required strength creating the works they perform.
"Allah is the Creator of all things." (Zumar, 62)
"To Allah is your return and He hath power over all things." (Hud, 4)
"Allah. There is no god but He,-the Living, the Self-subsisting, Supporter of all." (Baqarah, 255)
"Why didst thou not, as thou went into thy garden, say: 'Allah's will (be done)! There is no power but with Allah.' If thou dost see me less than thee in wealth and sons." (Kahf,, 39)
"Regulating and governing all things." [Jonah, 3]
"He directs the affairs from the heavens to the earth." [Sajdah, 5]
"He Who created all things in the best," (Sajdah, 7)
"We have indeed created man in the best of moulds." (Tín, 4)
"But Allah has created you and your handwork." (Saffat, 96)
"Him Who created thee. Fashioned thee in due proportion, and gave thee a just bias." (Infitar, 7)
"Allah is free of all needs from all creation." (Ankabut, 6)
"Of Him seeks (its need) every creature in the heavens and on earth: every day in (new) Splendor doth He (shine)!" (Rahman, 29)
"There is no moving creature on earth but its sustenance dependeth on Allah: He knoweth the time and place of its temporary deposit: all is in a clear Record." (Hud, 6)
"Allah hath full power and control over His affairs; but most among mankind know it not." (Yusuf, 21)
# The created things are mortal, their existence depends on Allah
"Physical world" and "Spiritual world" are mortal because they are created realities, which mean they have a beginning and end. Their existences are not forever. Their existence can long forever if Allah (swt) let them survive forever.
Materialist philosophy tries to replace "Material world" with Allah (swt) because it does not accept the existence of Allah (swt), far from it. It defends that "material world" existed itself without a beginning and an end. However, their thesis was disproved by the findings of modern science. In fact, Materialist philosophy cannot explain various things as a philosophical discipline.
Dear Readers, all the creatures of the created worlds except Allah (swt) are at imagination stage. The information that human obtain from the order he is in is a "perception" information. Human can understand the world to an extent that he can perceive. Perception is giving meaning to sensations (imagines in one sense) of our sense organs by the mind. Human knows the creatures with these perceptions and decides if they exist or not. Let me give an example. A soldier cannot see anything in the dark but when he looks with thermal cameras, he sees the enemies. What happens here? In the first situation, there is no enemy as there is no conception. In the second one, there are enemies because they can be perceived. It means that we only accept existent what we can perceive.
# The weak human only accepts the existence of the things they can perceive
We accept a material's existence because we can perceive its features as its color, shape, weight, voice, and smell. Every quality that we can perceive is an information. If we do not perceive any of the qualities, we do not accept the existence of a thing even it really exists.
In fact, the human is the acceptor of the sensations from an object rather than the object itself. The perceptions are embodied as object concepts with various features by giving meaning with previous information in our minds. Therefore, the world of which existence we accept is an imaginary world, which is created by processes of various nerve and brain functions. Its difference from the dream is that it has rationality and continuity, which is provided by Allah (swt).
Therefore, Rasulullah (s.a.w) ordered:
"Human beings are asleep when they die they wake up" [Imam-ı Rabbani]
It is true that human beings are aware of the absolute reality when they die.
Be entrusted to Allah.