Partially influenced by ancient Roman and Greek mythology, Christians can often think of heaven as a physical location and sometimes point to it in the clouds.
In Western culture its common to imagine heaven as a place where God lives, looking down at us from his white throne.
Yet, the Catholic Church teaches that heaven is not a physical place.
What is heaven?
The Catechism of the Catholic Church reflects on the nature of heaven in its section on the Lord's Prayer:
This biblical expression [Who art in heaven] does not mean a place ("space"), but a way of being; it does not mean that God is distant, but majestic. Our Father is not "elsewhere": he transcends everything we can conceive of his holiness. It is precisely because he is thrice holy that he is so close to the humble and contrite heart.
Heaven is a "way of being" and does not take up physical space.
At the same time, we do need to use human words to try and describe what is indescribable:
The symbol of the heavens refers us back to the mystery of the covenant we are living when we pray to our Father. He is in heaven, his dwelling place; the Father's house is our homeland. Sin has exiled us from the land of the covenant, but conversion of heart enables us to return to the Father, to heaven. In Christ, then, heaven and earth are reconciled, for the Son alone "descended from heaven" and causes us to ascend there with him, by his Cross, Resurrection, and Ascension.
We can see glimpses of heaven on earth, whenever we let God dwell within our hearts.
These glimpses then point us to our final destination, which is total union with God:
When the Church prays "our Father who art in heaven," she is professing that we are the People of God, already seated "with him in the heavenly places in Christ Jesus" and "hidden with Christ in God;" yet at the same time, "here indeed we groan, and long to put on our heavenly dwelling."
The good news is that heaven is not a royal palace on top of the clouds. Instead, it is a total union with God, whose love and mercy will surround us for all eternity, while also joining us to all those in union with him.
