The concept of afterlife, Heaven and Hell is almost universal to all religions and cultures. But to understand these as per the correct Orthodox perspective, we need to get our terms right. Let us consider the following terms:
Difference between Hades and Gehenna
The English word Hell is often used (especially in KJV Bible) to denote both Sheol (Hades) as well as Gehenna [Issues of translation].
These two are not the same, and when these two words are translated into the same English word 'Hell' it causes confusion.
Hades is the Greek translation of the Hebrew word Sheol. The literal interpretation of Sheol (Hades) is 'place or state of the dead'. The Malayalam word used to denote Hades is ‘paathalam’. Gehenna does not exist yet; it comes into being only at the Second Coming of Christ. The Malayalam word used to denote Gehenna is 'Agni Naragam'.
Prior to the crucifixion and resurrection of Jesus Christ, all the departed souls were captives in Hades. Jesus Christ descended into the abode of the dead (ie. Hades) and set the captives free. So in that sense the old Hades, where souls are kept captive does not exist anymore.
But Hades, where the departed souls await their final judgment, still exists. We can see the difference between Sheol and Gehenna from the following hymn from the s'Himo (sheema) prayer for Monday morning.
Similarly Paradise and Heaven are not the same either. Paradise also called 'bosom of Abraham, Isaac and Jacob' exists now. However the full glory of Heaven happens only after the Second Coming of Christ in his all glory. We will see this in more detail later.
What happens to a person after death?
Death is nothing but the separation of the soul from the body. At death the person enters into a state of rest. This is why we say such and such person fell asleep in the Lord. At death the soul does not immediately go to Heaven or to Gehenna. That does not happen till the final judgment and it occurs only with the Second Coming of Christ. During the Second Coming of Christ, all the dead will rise again and the souls will be reunited with their renewed body. Everybody will receive everlasting life; some will enjoy that everlasting life in Heaven while others will experience it in Gehenna.
So what happens to the soul immediately after death?
Think of two students preparing for the year end final exam. One student studies well, and comes into the exam hall very relaxed and takes the test. He is not distracted. As soon as he walks out of the exam hall, he already knows that he has scored 100/100. He is already experiencing the joy of having received the promotion to the next class and enjoys the summer holidays. But remember he is not in the next class yet. That happens only when the results are announced. Now think of another student, who did not prepare well. He is not very relaxed when the time to take the test comes. He is very nervous to enter the exam hall. He is much tensed. When he walks out of the exam hall, he is still tensed. He does not know if he will pass or fail. He will spend his entire summer vacation worrying about the day when the results are announced. Keep in mind, this student has not failed yet. He is also waiting for the results to be announced, but unlike the first student, he is not relaxed or at peace.
The state of a soul after death, till the Second Coming of Jesus Christ, can be understood somewhat like the state of mind of these two students waiting from the day of the exam till the day when the results are announced. Though both the students are in the summer holiday period, the way they are experiencing the summer holiday is not the same. One is happy and is at peace, the other is anxious and tensed.
All departed souls are in Hades. None of these souls in Hades are captives as they were before Christ. Some of the souls in Hades now have no rest or peace; but some of them who have fought a good fight and kept the faith, is already experiencing the peace and joy, while awaiting the Second Coming of Christ in all His glory. This state of experiencing Hades in peace and joy is what the Church calls 'Paradise' or the 'Bosom of Abraham, Isaac and Jacob'.
This understanding is what we see in the 'Prayer of Mor Balai' (Anugrahangal Niranjirikkunnavane), that we recite in every prayer:
O! merciful Lord, renew us Thy creation on the day of resurrection.
O! Lord, grant rest and peace to our beloved departed ones who have lived and died with hope in Thee, and is looking forward to Thy second coming.
O! Lord grant rest to our faithful departed in the bosom of Abraham, Isaac and Jacob.
May the souls and bodies together cry aloud and say: glory be to the one who has come and is to come to resurrect the departed.
Hades, both Hades proper and the bosom of Abraham, Isaac and Jacob is not a place that is devoid of the love and presence of God. As we read in Psalm 139:8 "If I ascend up into heaven, you are there: if I make my bed in Sheol (Hades) , behold, you are there."
In the parable of 'The Rich Man and Lazarus" (Luke 16:19-31) our Lord paints a good picture of Hades and the 'Bosom of Abraham, Isaac and Jacob' (Paradise) for us. We get a good understanding about the state of souls after death and before the 'Second Coming of Christ'.
What happens at the Second Coming of Jesus?
The second coming of Jesus and the final judgment are the one and the same thing.
Just think of the sun. It is so bright that we cannot look into the mid-day sun with our naked eyes. Think of a man who was spending couple of days in a dark room with no light. The pupils of his eyes will become dilated. Now all of a sudden if that man is brought into the mid-day sun, the brightness will blind him. He will not like the bright light. He will long to go back into the darkness, because his eyes are more used to the darkness. Now assume that the dark room does not exist anymore. There is just brightness everywhere. Where will this man run? He has nowhere to run to.
Now think of another man reading under a light. This light may not be as bright as the sun, but it is still a light. Now if this man is brought into the mid-day sun, he will not run away from the light. The pupils of his eyes are not dilated as he is used to the light. He will enjoy the brightness, as he can all of a sudden see much more clearly than before. Things that he could not see in the not so bright light earlier are all of a sudden visible in the bright light. This man will enjoy the brightness.
It is the one and the same bright sun. The man that loves darkness hates the bright light and he experiences it as torment. The man that loves the light loves it and enjoys the enhanced vision the bright light gives him, which he didn’t have before.
Now think of the transfiguration of Jesus that happened on the mountain, described in the Gospel of St. Matthew 17: 1-9. There we can read that the face of Jesus shone like the sun and his clothes were bright as light. We also read that even the disciples fell facedown and were terrified at that occasion.
When Jesus returns, He will come in all His glory and light (Matthew 25:31). It will be many more times powerful than what occurred on the transfiguration mountain. The sun is just one of the millions of stars created by our Lord. We cannot even imagine the brightness of the uncreated light of our Lord. Those who love Jesus and followed him in thoughts, words and deeds will enjoy this divine energy of Jesus and bright light; those who didn’t will experience it as fire and burning.
We read in Hebrews 12:29 that: "Our God is a consuming fire." At the second coming of Christ, the flame of the living God, who is a consuming fire, is joy and peace and refreshment and glory for those who believe Him and love Him, but is torment and agony and Gehenna for those who do not.
Gehenna is not a place where the unrighteous are cast away from the presence of God. God is omnipresent. He is present everywhere. There is no place where God is not present.
This is the understanding we get when we read 2 Thess 1:9, which says : "These shall be punished with everlasting destruction from the presence of the Lord and from the glory of His power." So the just are experiencing glory and peace and beauty and bliss from the face of the Lord, and the evil are experiencing torment and agony and punishment from the face of the same Lord, in the same reality.
So Heaven and Gehenna is the same reality; namely the Second Coming of Jesus in all His glory and might. Those who love Him experience it as Heaven and those who don’t experience it as Gehenna.
We have a good imagery of this in Daniel Chapter 3. Consider Shadrach (Hananiah), Meshach and Abednego, who refused to worship the idol in Babylon. They were thrown by King Nebuchadnezzer into the "fiery furnace" which was heated "seven times more" (Daniel 3:19). The significance of "seven" is a number symbolic of the "furnace" of Heaven. The three Jews were unharmed by the fire where one "like the Son of God" was among them (Daniel 3:25). However, the same flames of fire killed the king's "most mighty" soldiers (Daniel 3:22). This is an analogy to how the presence of God is light and warmth to those who love him, and pain and destruction to those who oppose him, yet it is the same "fire."
We also see this in Psalm 68 on how the wicked and the righteous experience the same reality of the presence of God differently. We read in Psalm 68:2-3
As wax melts before the fire,
So let the wicked perish at the presence of God.
But let the righteous be glad;
Let them rejoice before God;
Yes, let them rejoice exceedingly.
We again see this same idea conveyed to us in the Holy Qurbana (Divine Liturgy). Towards the end of the Holy Qurbana, during the 'Procession of the Holy Mysteries', just before turning east and retuning to the altar, the priest recites the following prayer:
" Glory be to You, glory be to You, our Lord and our God, forever. Our Lord, Jesus Christ, let not Your Holy Body, which we have eaten, and Your Atoning Blood, which we have drunk, be unto us for judgment nor for revenge, but for eternal life and for the redemption of all of us, and have mercy upon us." [WATCH IN YOUTUBE]
Here we can see the 'Holy Body' and 'Holy Blood' of our Lord, could be judgment and revenge for us OR the redemption and eternal life for us. It is the very same true presence of our Lord in the Holy Eucharist, but the way people experience it is different; for those receiving it with faith and preparation it is for redemption and eternal life , for the ones approaching the chalice without faith and repentance it is for their judgment and revenge.
The Orthodox understanding of Gehenna is clearly summarized by St. Isaac the Syrian (Mor Isahak) :
"I say, that those who are suffering in hell, are suffering in being scourged by love.... It is totally false to think that the sinners in hell are deprived of God's love. Love is a child of the knowledge of truth, and is unquestionably given commonly to all. But love's power acts in two ways: it torments sinners, while at the same time it delights those who have lived in accord with it" (Homily 84).