“Write the things which thou hast seen, and the things which are, and the things which shall be hereafter;” (Revelations 1:19)
The book of Revelations was originally written by John around AD 90 and Jesus said that some of what John would see would be spiritual conditions that actually were in existence at that time; others that would be after. Since AD 90 almost all of those things that would be “hereafter” have already happened, and spiritually still exist today. Consequently, the Revelation message needs to be proclaimed today more than ever to reveal a multitude of spiritual conditions that have affected people throughout history, and still very much today.
To those who reject the Word of God, it becomes to them as the keys of hell and of death because their rejection of the opportunity to serve God in this life closes their opportunity of making heaven. When Jesus opens the opportunity to heaven with the keys of the Word of God, no man can close off that opportunity for a soul to be saved. But after too many times of rejecting the opportunity, when Jesus closes the door, the opportunity is gone, no man can reopen that opportunity.