system
Given the following post, respond as if you're commenting on Reddit:
human
CMV: Stannis did nothing wrong (all show spoilers)

Stannis Baratheon just barbecued his daughter and was completely justified in doing so. In fact he was morally required to.

First semi-aside: Melisandre has proven magical powers. She's a sadistic psychopathic religious zealot but she didn't just knock on Stannis' door and ask her to speak about the fire lord. She has delivered before under similar circumstances and trusting her to do so now is reasonable.

Now the real point: The lives potentially and actually saved by Shireen's sacrifice (somewhere between "a few dozen" and "everyone in Westeros for the next million years") demanded it. Stannis' men are dying in the snow. He loses more every day of the siege. His camp will break before Winterfell does, and his forces cannot overcome Winterfell's defenses. He can neither continue the siege nor attack.

Is Shireen's life worth ten of his men's? A hundred? A thousand? The lives of everyone who stands to starve or be killed by the Bolton's if he fails? The lives of everyone in the North, present and future, who would suffer under the Bolton administration?

Is it worth the lives of the millions who will die and the many more millions who will never be born if the Long Night falls once again?

Against those stakes the life of one person must be sacrificed for even the most minimal bump to humanity's chances for success. Even if she's a sympathetic little girl who didn't sign up for this and who we are made to, rightly, like.

Wasn't she just going to die in the snow or suffer some terrible fate as a Bolton captive if things kept going as they were anyway?

This is the classic ethical hypothetical about whether or not you should throw a switch to kill a cable car with 10 people in it in order to avoid a catastrophe that will kill 100. Stannis has thrown the switch on his own daughter for, at a minimum, the end of a siege where people are dying in droves and will result in the victory of a family of vicious tyrants. On the upper end of the possible scale, the stakes are the safety of Westeros from the White Walkers for the next hundred thousand years.

This was an agonizing sacrifice for him to make but it was done in the credible service of a battle where the consequences very well may include the future of everything. And given the situation, Shireen probably didn't lose a long life of regal comfort wisely ruling Westeros so much as she lost a short life of freezing until she was killed by the elements or the Boltons. 

Stannis did nothing wrong. CMV.
gpt
Your whole argument rests on the assumption that sacrificing Shireen was *necessary* to gain the favor of the Lord of Light.  Thoros of Myr has brought Berric Dondarrion back to life how many times, now?  And all without a single sacrifice.