“What no eye has seen, nor ear heard, nor the heart of man conceived, what God has prepared for those who love him” (1 Cor 2:9).
However, I think there are two goods we will certainly enjoy completely in heaven: Peace and security.
Peace is being in a state of friendship with others. Security means the goods you possess, whether spiritual or material, cannot be taken away.
In our current condition, we know what peace and security are, have experienced them at times, and work to attain them, but anyone and anything can harm us and what we enjoy can be taken from us instantly at any moment.
Catholic theology’s explanation for this condition is called the loss of original holiness and justice.
Very simply stated, loss of original holiness means we are no longer in friendship with God.
This condition of being in enmity with God is a problem on our part even for the baptized. The reason for this is because God’s friendship requires effort, like doing things we find hard and not doing things that seem delightful. In addition, a part of us longs to betray him, tugged by the allure of the good things of this world and counterfeit heavens we imagine can create.
The loss of original justice means we are no longer friends, or in a right relationship, with ourselves, with other persons, and with the natural world. We can hurt ourselves and other people, people can hurt us, and the natural world can harm us. This is why fear and suspicion are our constant and even “healthy” companions in this fallen world, even though they gnaw away at us and can make us doubt everyone.
However, in heaven we will be in a perfect friendship with God. He will be our loving father and constant companion and we will be his perfect sons and daughters. We will know, feel, and experience profound peace and security in our relationship with God.
In heaven we will also be in a state of friendship with all creatures. No one and nothing will be able to hurt us, nor will we be able to hurt anyone else, so we don’t even have to be afraid of ourselves. There will be no fear.
Peace and security have to be qualities of heaven. Peace comes from being in friendship with everyone and everything. Security comes from never being in danger of being harmed or having any good thing taken away.
I think this is one reason why the first thing Christ says upon rising from the dead is, “Peace be with you” (Jn 10:19).
Security as a quality of heaven is witnessed in Revelation when St. John writes about the descent of the New Jerusalem:
“Behold, the dwelling of God is with men. He will dwell with them, and they shall be his people, and God himself will be with them; he will wipe away every tear from their eyes, and death shall be no more, neither shall there be mourning nor crying nor pain any more, for the former things have passed away.” (Rev 21:3-4)