From the throne came flashes of lightning, and rumblings and peals of thunder,
When God delivered the Ten Commandments to Moses on mount Sinai, the people of Israel were totally terrified. The mountain smoked and shook. Thunder, lightning, and rumblings reminded the onlookers that the God of the Bible is not a God to trifle with. He is dangerous. He is deadly. His holiness will destroy the sinful.
Here, as john looks at the throne, he lets us know that god has not changed. Whether in the Old Testament or the New, God is still holy. His holiness is still deadly and terrifying. He is still not a God to trifle with. He is still a God we approach with the utmost of reverence.
There is, of course, room in our worship for joyful celebration. Such is present all through Scripture. But, and this is important, the closer we get to the actual glory of God, the more we tremble. There must be reverence and not casualness in our worship. We dare not be flippant about coming before our God. He is far too powerful and far too holy for that.