What does Revelation 4:2 mean?

In this verse John relates he was in the Spirit when he beheld a throne that stood in heaven. Perhaps the Holy Spirit transported John or his spirit to heaven, or John was seeing a clear vision of what was happening there. His first gaze fell on a firmly established throne, on which sat God. Isaiah had a similar vision of the Lord sitting upon a throne, "high and lifted up" (Isaiah 6:1). The image of God on a fixed throne indicates that He is sovereign, King over all creation. It also indicates that nothing can shake His throne. Nor can anyone, whether the Devil or an earthly ruler, topple God from His throne.

John is about to see future events that cause unbelievers on earth to panic, but God originates those calamitous events as judgments. While these events may inspire sadness as they occur to non-believers (2 Peter 3:9; Ezekiel 18:23), they do not trouble God. Nor do they change the destiny of those who are Christians before the rapture, who will be in heaven when the judgments fall on the earth (Revelation 3:10). The fact that God is seated on a throne should calm whatever fears assail believers. He is in control!