Wednesday night at sunset begins the seven-day festival, "The Feast of Tabernacles", which pictures the Kingdom of God ruling over the earth during the millennium. The millennium is the period of time for one thousand years when Christ and the resurrected saints rule the earth (Revelation 20:1-9).
But the millennium is not the Kingdom of God. The millennium is a period of time lasting one thousand years. The Kingdom of God will go on forever.
The Kingdom of God is the government of God that will rule over the earth during the millennium, and it is also the family of God, or "God Family". Flesh and blood human beings living on the earth into the millennium will not be IN the Kingdom of God while human during the millennium, but they will be RULED BY the Kingdom of God, with justice and love. And they will have the opportunity to hear the true gospel, to believe the gospel, to repent, and to eventually enter into the Kingdom of God also. Salvation will finally be open to all.
The Kingdom of God will include Jesus Christ and all the resurrected saints made immortal and made full Sons of God. As part of God's family, we will live forever in power and glory and joy. With Christ we will rule the universe. The millennium is just the beginning.
God does not give many details of what projects we will be working on in the vast universe for millions, billions, or trillions of years into the future. But there is a great deal of information about what we will be doing in the millennium. We will be kings and priests helping Christ rule the nations on this earth (Revelation 1:5-6, 2:26-27, 3:21). And the Bible is full of information about what life will be like during the millennium, and much of this information will be related and expounded upon by God's ministers in Church of God Feast sites all over the world during the seven days of the Feast of Tabernacles.
It will be a period of great happiness, peace, prosperity, and justice.
God commands us to gather to observe the Feast of Tabernacles and to rejoice. We are to spend the second tithe we have saved for a year to enjoy food and fellowship that will help us to have a small foretaste of the prosperity and happiness that will exist all over the earth during the millennium (Deuteronomy 14:22-27).
There are really two aspects of the joy that the Feast of Tabernacles helps us understand.
One, there will be the happiness that will exist on the earth among mortal human beings when the nations are taught to obey all of God's laws. Satan will be put away and people will learn the truth about God's way of life that results in happiness. The Kingdom of God will teach mankind God's law and enforce peace and justice.
But also, we ourselves who will be IN the Kingdom of God and part of that Kingdom will experience a joy we can only partially imagine now. We will share in the power, glory, and joy that Jesus Christ experiences now (Matthew 25:20-23). We will live forever with no fear of death. We will finally be free of human nature and temptations to sin. And we can look forward to ever increasing accomplishments working with the whole vast universe that Christ presently rules. And this will go on forever.
During the Feast we will have many opportunities to enjoy food, fellowship, service, and fun that we do not experience during the rest of the year. But we should not get so wrapped up in just the enjoyment of the moment that we forget what that enjoyment is supposed to represent. It represents the happiness we will enjoy in the Kingdom of God and it represents the happiness mankind will enjoy during the millennium when the Kingdom of God is ruling the earth.
Here are links to related sections in Preaching the Gospel:
The Feast of Tabernacles - the Millennial Rule of Christ, Chapter 2
God's Purpose for Mankind, Chapter 2
The Gospel of the Kingdom of God, Chapter 2