If you believe in eternal torture or happiness after death, basically anything is justifiable here on Earth to bring someone to your side or prevent them from "falling" to something that would land them in the bad place. In fact it's not just justifiable but a moral imperative if you believe you can save someone an infinite amount of suffering even if you cause temporary suffering now.
If someone believes in a god that implements eternal torture, they believe in a god everyone should despise, and should at least be honest about that part. Don't call it love, call it fear and terror.
The idea of a life after death where an idyllic eternal life can be simply purchased with belief demeans and devalues this life. You will never convince me that someone believing such things would be more moral and ethical than someone who believes that this life is all we get. I would argue that such belief is a cornerstone to a lack of ethics and morals because it implies nothing in this life really matters.
If the only reason you don’t harm others is so that you’ll get a place in paradise, you are not a moral or ethical person, you are a an egotistical hypocrite and a fake “good person”. Non-religious people who don’t harm others simply because they respect them and just don’t want to harm them, are the truly moral ones.
It doesn't imply that nothing in this life really matters. It implies that belief and living a life following the moral code outlined in the respective book and interpreted by the respective religious authorities is really important. That's the whole ruse and why religion like this works tremendously in achieving its goals.
The violence isn't caused by the hell belief; it's institutionalized by the hell belief. Abusive, violent, hellfire religion is an institutionalization of the habits of abusive, violent parents. Get rid of the actual physical child abuse, and the violent doctrine has nothing to sustain itself.
Hell is just a metaphor for how terrible it is when your parent screams at you and beats you. To a small child, while that's happening, it is eternal. You are wholly condemned, wholly guilty and judged, and no part of you is safe from pain and punishment. The doctrine of hell is religion telling you that's normal.
Without hell religion, kids who are beaten by their parents might grow up to beat their own kids. Or they might get over it. Or they might not have kids at all.
But under what circumstances do you get generations of kids getting beaten, growing up, having kids, and beating those kids too?
That's where hell religion comes in. It tells you that the beating isn't just your parents being terrible people; it's an explicit command from God, who created the whole universe. It's not just your parents, it's how the whole world is supposed to be. And you're supposed to grow up and do it too.
Hell religion tells you that it's wrong to recover from the abuse that was done to you. Stay traumatized; stay violent; put on the character armor of God and raise the rod to your own child so that they stay on the same shite-and-narrow path that you were put on.