What does Revelation 4:1 mean?

This verse begins the last, largest portion of Revelation. This writing began with a description of John's reception of this Revelation, and a message from Jesus to seven churches which existed in John's era. This segment describes those things which were yet to occur when John saw this vision. After describing messages to seven churches in chapters 2 and 3, John is now given information regarding the "end times" of the world.

In this verse we read that the apostle John saw an open door in heaven, and heard a voice which sounded like a trumpet. This is the same voice that spoke to John earlier (Revelation 1:10–11). Later, John specifically identified the voice as belonging to Christ (Revelation 1:12–18).

The open door symbolically affirms that God has made heaven accessible to human beings. Of course, admission is available only to those who believe on Jesus as their Savior. Speaking to His disciples about heaven, Jesus said, "I am the way…No one comes to the Father except through me" (John 14:6). John, who recorded those words from Jesus and now sees an open door in heaven, was a believer and therefore already held assurance that he would enter heaven someday. However, seeing the open door in heaven when he lived in exile on Patmos must have surprised him. Jesus beckoned John to enter heaven, where Jesus would show him future events.

John's experience compares closely to the rapture of the Church. Described in 1 Thessalonians 4:16, the rapture occurs with a voice, the sound of a trumpet, and all believers experiencing being caught up from the earth.