As the law is written on our hearts, you don't even need to be a Christian to see that tyranny is wrong. When a bad government does bad things, it is actually better to suffer whatever punishment they give you than to go along with them. Take the obvious example of the Nazis. If you hid Jews from them, you were executed. Yet, because they were killing Jews, your sacrifice would have been a worthy one.
Many atheists, unfortunately, see God in the same way. In their mind, even though God has the power to send us to Hell, it might actually be better to accept that punishment than to worship Him. This falls under the same concept of "speaking truth to power". In other words, standing up to injustice.
But my friends, I want you to think about the logic of this. First of all, while most of us agree that the government is actually a "necessary evil", how many people who suffer its punishments will actually agree that they are just in dishing out that punishment? Sure, you have some people, like my step dad, who will happily accept, for example, a speeding ticket if he was caught speeding. Other people, however, will believe they are justified in committing terror attacks, believing the government they were trying to topple is illegitimate. Speaking truth to power only works if there is a truth to speak. Yet, that truth must inevitably be based on a greater power that upholds it.
As a Christian, I believe government powers are both legitimate, and limited. Romans 13, which was conveniently written by a persecuted citizen under the rule of tyrants, tells me to obey human governments, and also tells me why they exist. A good government is a terror to evil, and will praise good. It only becomes a problem when it fails in that regard, and when it does so, we should rebel only in that case. Even the aforementioned Nazi regime, while it should absolutely have been opposed in its treatment of anyone it considered inferior, still had the legitimate authority to punish murderers, rapists, thieves etc. Without a government, we have anarchy: Every man does what is right in his own eyes. And anarchy is just barely preferable to excessive tyranny.
The thing about God is that He also does what is right in His own eyes. And frankly, He is more than qualified to do so. See, you cannot speak truth to God, because God has access to more truth than you. In fact, while even the entire human race has never had an especially firm grasp on our own tiny corner of the universe, God has access to all truth. The stars we can't even count, God knows by name. And He controls it all with His words. When He said "let there be light", there was light. When He told the storm to be quiet, it happened in an instant. So, what truth do you possibly imagine you could speak to God?
To put this into perspective, consider your own childhood. All of us had some pretty crazy views as children. I remember in my own youth, we had a little photocopier. You put a thing on the scanner, pushed a button, and the printer would immediately spit out a replica. So of course, I had the genius idea that we could get rich quick. All we had to do was copy some banknotes several times over. One £20 note in the scanner, press the button several times, and boom, we could easily have enough money to buy me all the dinosaur toys I wanted! Hooray!
So I took that idea to my mother, who of course laughed it off. Kids say the silliest things, don't they? But when I was that kid, I didn't think it was silly. I kept asking her why we couldn't do it, I kept telling her we should at least try, I wouldn't accept her claims that printed money was both noticeably different from real money and very much illegal even if you could make it look real. Would it not have been wiser for me to just accept that maybe, with her significantly greater life experience, my mother knew what she was talking about? I couldn't tell her anything she didn't already know, and because of that, it was also foolish for me to act like I knew better.
As an adult, I now understand why counterfeiting is both foolish, and actually carries a just penalty. If you make fake currency, you deserve the punishment you receive, because it actually affects all of us. Seeing the folly of my childhood also allows me to see the folly of many adults today. There is a far greater gap between me and my God than there ever was between me and my mother. In fact, if we could gather together all the knowledge held by every human being who has ever lived, or will ever live, from Adam to the last ever newborn, the resulting mind would be really quite derpy when compared to God. So what do we imagine we could tell Him? "Hey God, you're wrong, because although I know next to nothing and you know literally everything, here's this one opinion I hold that you really ought to listen to". It's just not going to work is it?
So, rather than being a noble sacrifice, being willingly condemned to Hell is actually quite the waste. If you're "brave" enough to think you could handle Hell, what you're actually doing isn't speaking truth to power, but allowing yourself to be swallowed up by your own folly. See, God knows all of your sins. God even knows sins you have forgotten about. God knows sins in your life you haven't forgotten about, yet regret. And in fact, the irony is, you may not even have originally regretted them. How many of us now regret things that, at the time, we were quite proud of? I certainly do. I was proud of many of my sins. I regret them now by grace of God, but there was a time when I thought I was doing the right thing. My atheist friends, even if you think you are somehow justified, God knows you're not, and one day, you will too, because a time is coming when every knee will bow. And not even by force, because seeing the Lord will open your eyes in the same way becoming an adult did.
The scary thing is, the punishment some atheists think they would willingly receive because God is a tyrant is actually the just punishment, because God is Holy. The real injustice, therefore, is not only taking it in pride, but also failing to help others avoid it. See, though God is Holy, God is also gracious. Sin deserves punishment, yet out of love for sinners, God is willing to personally take that punishment Himself. When an atheist chooses Hell, they are wasting their own unearned rewards, for a punishment they deserve, yet nevertheless ought not take. But on top of that, they are leading others in their folly. Tell me, if you really object to Hell, which is better? To take as many people there with you as possible in some misguided protest, or to serve God in His attempts to bring salvation to those who actually deserve Hell?
Hell is not a nice thing to discuss. I don't like it, you don't like it, God Himself hates Hell so much that He nullified it with His own blood. The existence of Hell does not make God unjust, but just. The existence of Heaven? Well that just makes God more gracious than we have any business asking Him to be. Therefore, repent, and be baptised, because why, oh why, oh why, would anyone, being freed from a huge debt, say to the one who rescued them "you're mean because I ran up a debt with you, therefore I will not accept your cancellation of my debt at your own expense. Rather, I will commit to paying it myself"? Don't be a fool. Get saved.