You could just toss the ball back to them, so to speak. For every negative comment hurled at you, simply change a couple of words and deflect the anger back to them. I am becoming an expert in this category, although it is still hard. I sadly understand what you are going through firsthand, just not so much with my parents but with another family member.
* As to religion, God is about love, not hatred. Jesus embraced Mary Mandolin, not threw stones at her.
* Who made your parents judge, jury, and executioner? Did they personally talk with God? How do they know that God did not approve? God knows everything and is perfect, so if he did not intend for a biological diversity, then he would not have made transgendered people.
* Pushing forward, do your parents drive or have been in any type of motor vehicle? Have they ever flown on an airplane? These things are sacrilegious. "If God meant humans to fly, He would have given them wings." Oh, he gave them the ability to create wings? Okay, he gave them the ability to stand up to bigots and get the courage to transition too!
* It is up to parents to love their children and stand by them no matter what, not throw hatred their way.
* With your hatred that you show towards others, it is not "I" that will go to hell, but sadly "you," as I am not the one hating and having black clouds hanging over my head, but you.
The list goes on, but you have to be strong. Sadly, it is your parents, which makes it harder, at any age. Partners are hard too.
Maybe one day, they will come around. Let us all hope for the best.