The Hereafter, Akhira

The concept of Akhira is the foundation of Islam. It's a simple concept based on logic and specific fixed laws. It is not a mystery or an enigma. In simple terms, it means that whatever we do in this world will bring us consequences, and Akhira or the Hereafter is the phase where every human being will know them and understand the nature of life that they will live in the next phase of existence. This concept proves the existence of a higher authority and the idea of life after death and asserts the supremacy of justice. Not every action we perform in this world is known or open. The Hereafter will record and reveal everything that we do in this world.

The universe we live in is not a haphazard entity. Everything that exists in it follows specific laws.  We call them. The laws of Return and they are fixed. Every action taking place in this universe creates its reaction and consequence. We notice some reactions immediately and others later. The reaction and consequence are fixed. For instance, if we do not know how to swim and we throw ourselves in Deep Ocean, according to the Law of Return, we would perish.
The Quran such consequences immutable and divinely created scales or criteria.
This has been Allah's Sunnah (practice), and there will never be a change in this  (48:33, 17:77, 35:43) : "… the scales fixed by Allah...(33:38)"

The laws are self-evident in the physical universe. In the spiritual world, sometimes, the consequences appear instantly and sometimes later. This concept of Law of Return at a later phase of existence is the foundation of the Hereafter.
Thus the concept of a hereafter is the logical culmination of the Law of Return. Akhira or Hereafter is the concluding phase of existence. Akhira is the essence of faith. It leads to the beginning of a new phase of existence that is different from the previous one. The word Akhira is used in r different meanings in the Quran.
There is a tomorrow or a future for everything present
The tomorrow of individuals emerges from their today.
There is a tomorrow for humanity
The tomorrow of humanity comes on the heels of its existence in the world
The tomorrow of humanity is different than its today
The ultimate tomorrow of individual and humanity is the ultimate Akhira that would close every chapter of today and usher in into  a new phase

The belief in the Hereafter completes one's faith in divine guidance. The Quran describes the believers  …and (in their hearts) have the assurance of the Hereafter. (2:4) See also (27:3, 31:5)
The Quran declares the belief in the Hereafter as a fixed condition for understanding divine guidance. It describes those who do not believe in this concept as Mushrik or a polytheist. Furthermore, it says that Evil forces can quickly overtake those who do not accept the Hereafter as the ultimate reality.
This concept asserts the supremacy of the Law of Return. There will be a world where everything human beings do in this world would be accounted for, and consequences will be delivered, and a new beginning of existence will come into being.
The Law assures that human beings will exist after death, and the Qiymat is the phase of the physical resurrection of human beings. This resurrection will be a huge assembly, and every action that human being indulges in the world would manifest itself before everyone
What happens after death? The common belief among Muslims is that after death humans body will receive punishment or reward. The Quran does not say so. It mentions two deaths and two lives
They will say, our Sustainer, twice have you made us without life, and twice have you given us life! (40:11)
 How can you reject the belief in Allah - seeing that you were without life, and He gave you life; then will He cause you to die, and will again bring you to life; and again to Him will you return. (2:28)
Before we came into this world, we were dead, and our birth ushered into life. Death is the end of this life. After that, God will raise us again on the Day of Judgment. What the Quran calls Barzakh is an interim period between death and resurrection.
The Day of judgment would determine the final destination of every human being.  Those who did not believe in the concept of life Hereafter and the Law of Return and indulged in actions that defied the divine guidance would live a phase of new life that would be full of pain, turmoil, destruction, and upheavals. This life will be their hell.  Those who live their lives according to the divine guidance will have a life of peace and contentment, prosperity, success, and achievement.  This will be their paradise.
The life of these two categories of people will be eternal. Thus the concept of Akhira is to help human beings to prepare for eternal life. The Law of Return, based on the nature of consequences, will determine the final phase of one's eternal existence.