She burned around 300 protestants at the stake

Mary suffered terribly at the hands of her father. I think most of her mental and physical problems, including the phantom pregnancies, can be blamed on him. Becoming illegitimate overnight, her mother cast aside, her religious convictions scorned - it would do a number on most of us. Mary had been forbidden to see her mother for 3 years - all due to Henry's insistence that Mary submit to his will in declaring herself illegitimate and Elizabeth the true princess. Then her mother died, and I don't think Mary was ever the same after that. She channeled her frustration and grief into this religious fervor which she was as unable to control as queen as she was the rest of her life. Despite her horrific deeds, I cannot help but pity her.

What's wrong with protestants huh?