God and Jesus are two sides of one pretty amazing divine coin. On the one hand, you have God—creator of the universe and the mastermind behind all the wrath and destruction that is Revelation. On the other, you have Jesus. He's the Savior of the world and the vanquisher of evil so that's means he's a hands on kind of guy.
Revelation has (big theological idea alert!) a high Christology (source). This just means that the book sees God and Jesus as being equal in divinity and awesomeness. Unlike, say, the Gospel of Mark, where Jesus is portrayed as pretty human and separate from God. In Revelation, Jesus also has a special saving role to play in the world as the Son of God. He wasn't just some cool guy who walked around and said a bunch of interesting things. He is God himself in human form.
Still, it's pretty clear from Revelation that God and Jesus have very different roles to play in the end of the world.
For the most part, God kind of hangs back. He's just the "one seated on the throne" (4:2). John never describes God, except to say he "appeared like jasper and carnelian" (4:3), but he does talk an awful lot about his throne. But, come on, it's a rainbow that shoots thunder and lightning out of it (4:3-5), so how do you not talk about it?
God's also got a bit of a, well, God complex. Up in Heaven, he's the head honcho and he's surrounded himself by yes-angels. Literally everyone in Heaven is crazy for the Big Guy (4:9-11). Even when he violently murders most of the people on Earth, God can't go wrong. Rivers of blood? Great idea, Lord! Giant hailstones? High fives all around!
Speaking of violent murders, God is also the one who judges all the dead. He's the record-keeper for the Book of Life (and we're guessing he keeps pretty good records). If your name is in the Book, you're golden. If God can't quite seem to find your name on the list, you get bounced… to the Lake of Fire. Sorry, try calling ahead for reservations next time.
Jesus gets to do a little more than just sit around on a throne. He also gets to work undercover. In the beginning, John sees him as "one like the son of man," standing in the middle of seven candlesticks (1:13). Then Jesus appears to him as the slaughtered Lamb with seven horns and seven eyes (5:6). At times, he's just a random trumpet voice speaking to John (1:12). What can we say? He's mysterious like that.
But, later, Jesus gets in on the action:
• He's the only one with enough skills to open the seven seals (5:12-13).
• He teaches the Elect a lovely little tune (14:3).
• He brings the faithful up to Heaven (14:14).
• He rides out on a white horse and stabs the Sea Beast with his sword. Awesome (19:19-21).
It's pretty clear that God is kind of the mastermind behind the end of the world and Jesus is more of the "doer" in the relationship.
God and Jesus are probably the two most important figures in this book, if only because they set all the events in motion. Not only are they the source of the whole story (or so John tells us), but they also pretty much destroy the world together. That's no small task.
What do we make of that? Are God and Jesus just great guys/deities who want to bring the message of love and salvation to the world, or are they kind of jerky? Is it cruel to destroy the world, torture the non-believers of the Earth, and then cast them all down into the Lake of Fire? And is it wrong to do it, even if you're God?
Revelation is very clear that God and Jesus did give the world fair warning. After all, this book takes place over an entire millennia. If the rivers of blood and giant hailstones didn't convince the people to start listening to Jesus, what was going to? Maybe they deserved God's wrath and judgment, if only for being incredibly thick.
We also get the idea that really only God could pull something like this off. In fact, he's the only one who has the right given that he's the author of all creation. We guess in Heaven the rule is, "You bought it… feel free to break it." And God's not shedding any tears over these broken pots.
In Revelation, God and Jesus are a bit different than they are in other parts of the Bible—especially the New Testament. Sure, God gets a lot of play as a vengeful, wrathful guy: think Genesis 4:15, Deuteronomy 32:3, Isaiah 35:4, Luke 21:22, Romans 12:19. But he also has a soft side.
Jesus, on the other hand, is pretty much entirely different from any of the portraits we have of him in the gospels. Instead of kind and gentle teachings, he's leading the armies of Heaven into battle and smiting sinners left and right.
Sure, Jesus occasionally engages in some apocalyptic talk in the gospels. But, even Matthew 13:41-2—"The Son of man will send his angels, and they will gather out of his kingdom all causes of sin and all evildoers, and throw them into the furnace of fire; there men will weep and gnash their teeth"—looks downright quaint when compared to what Jesus is up to in this story.
Though most people prefer the lovey-dovey God, judgmental and vengeful versions of God pop up all over the place, too. Jonathan Edwards' famous sermon Sinners in the Hands of an Angry God depicts a divine authority who might cast the wicked into hell at any minute (but with good reason). In Catch-22, Yossarian complains that God can be kind of a warped and twisted jerk at times. Some research even shows that a belief in a vengeful God (as opposed to a loving God) makes people more moral overall.
Fear, apparently, is good. Maybe Revelation had the right idea, after all?