Just about every 2,000 years something great has happened from Heaven to in the world as we know it today. After the first 2,000 years, God sent the great flood upon the whole earth. Around the next 2,000 years, another great thing happened from Heaven; Jesus Christ was born of the virgin Mary. That takes up 4,000 years, so the next 2,000 years we are looking for the return of Christ. So, that completes 6,000 years of mankind. However, that leaves another 1,000 years to make the number 7 complete. That belongs to the reign of Christ for 1,000 years.
Also, we have 7 Dispensations: Innocence, Conscience, Human Government, Promise, Law, Grace, and Kingdom. We are now living in the Dispensation of Grace. Also there are 7 Churches in Revelation representing the church age, and we are living in the last church age. So, you see Christ can come at any moment. “Be ye ready.”