Q. 1. According to the Catholic Church, what is the Kingdom of God?
A. 1. First of all, I wish to point out that an entire book can be written on the matter. In short, the following summary would define the Catholic teachings on what is the Kingdom of God.
"The Kingdom of God" is also known as "The Kingdom of Heaven."
"The Kingdom of God" is a spiritual Kingdom. It is not of this world.
One's membership in "The Kingdom of God" is based on his union with God through Christ in the Holy Spirit.
The Mystical Body of Christ embraces the Kingdom of God. It includes all the baptised Christians who have accepted the salvation of Christ through faith, in the past, present and future, those on earth, those in Purgatory and those in Heaven.
In the days of the Old Testament, in included the believing Israelites.
"The Kingdom of God" may include other souls, who in the Divine Wisdom, which is beyond our human comprehension, have been adopted by God.