At the beginning of the Catholic Baptismal Rite the following questions are asked:
Priest: "What do you ask
of the Church?"
Priest: "And what does faith
Answer: "Eternal life".
We read in the Psalms,
"Before the mountains were born,
the earth and the world brought forth,
from eternity to eternity you are God. "(Ps 90:2)
From a time perspective God is eternal because He has no beginning or end. Actually God is the "I Am". The Philosopher Boethius states: "Eternity is the whole, perfect and simultaneous possession of endless life." (Boethius, The Consolation of Philosophy, Dover Pub., Inc., NY, 1962, p. 104) Some thought that this definition was not a good one because it contained the word "endless" or "interminable" which negates perfection.
St. Thomas Aquinas gave the following answer: "As we attain to the knowledge of simple things by way of compound things, so must we reach to the knowledge of eternity by means of time, which is nothing but the numbering of movement by "before" and "after." For since succession occurs in every movement, and one part comes after another, the fact that we reckon before and after in movement, makes us apprehend time, which is nothing else but the measure of before and after in movement. Now in a thing bereft of movement, which is always the same, there is no before or after. As therefore the idea of time consists in the numbering of before and after in movement; so likewise in the apprehension of the uniformity of what is outside of movement, consists the idea of eternity." (Summa, Part I, Q. 10, No. 1)
Now, in what sense do we participate in God's eternal life after death?
Granted that strictly speaking Eternity belongs only to God. Man being made in the image and likeness of God must in some way participate in God's eternity. Human participation in eternity cannot mean an "unimaginably long time" nor can it mean "unending time" because there is no time in God's essence. St. Thomas Aquinas thought man shares in God's eternity by never ceasing to exist. The angels likewise, participate in God's eternity because they are not subject to the biological processes of time (life and death) and because their knowledge is intuitive, not discursive. (Summa, Part I, Q. 10, No. 3)
On the other hand, man's purity of spirit is hidden behind a lower consciousness of thoughts, fantasies and emotions. Further, the lower soul is shaped by personal and cultural conditioning. Potentially, the human spirit ... is pure, formless, imageless awareness, unconditioned and uncompounded. Its aim and designation is to draw ever closer and unite itself to the Creator. Provided it is purified, it knows God and and the inner essences of created things through direct intuitive perception." (Hieronmonk Damascene, Christ the Eternal Tao, Vaalam Books, 2002, p. 277) In this way the Eternal life of man resembles that of the angels and Christ did tell us that we will live a life like that of the angels. Pope Benedict XVI expresses the realization of hope thus: "We can only attempt to grasp the idea that such a moment is life in the full sense, a plunging ever anew into the vastness of being, in which we are simply overwhelmed with joy. This is how Jesus expresses it in Saint John's Gospel: I will see you again and your hearts will rejoice, and no one will take your joy from you (16:22). ( SPE SALVI, No 12)
After death for those in eternity hope is no more because what they hoped for has become eternal life.
this is eternal life,
that they should know you, the only true God,
and the one whom you sent, Jesus Christ.