Selfish is expecting someone to stay miserable to save themselves possible embarrassment. My mom told me I was being selfish and that I didn't care how much shame and embarrassment I caused my family. That really bothered me. I worried that my dad and brother were were ashamed of me. When I first started my transition my brother once asked me why I always stayed in my room when my dad had his friends over and they always asked where I was at. I told him I didn't want to embarras my dad in front of his friends. He told me my dad wasn't embarrassed by me at all and that he showed his friends pictures of me all the time. I asked what pictures and he said since I always ran from a camera my dad took shots of me with his phone without me knowing it. Embarrassment over me being trans was entirely her problem. My dad and brother were never embarrassed by me being trans but she caused me a lot of stress telling me they were. If someone finds the fact you are trans embarrassing then you can spare them that problem by not having them in your life. They are the selfish ones, not you.
As for someone questioning their religious beliefs over a trans person then I would say that person's faith was weak to begin with. But again the solution to this problem is not having this person in your life anymore. Problem solved. Sometimes you have to cut people out of your life for your own peace of mind. It can be hard but sometimes you have no other choice. Unfortunately I had to cut my mom out of my life. I was so much more relaxed after she moved out of the house and even more so when she moved to another state.
As for someone not being trans because they weren't feminine and didn't try transitioning when they were very young, I myself thought the same way. I was always very feminine from an early age. My dad was always tolerant with me and didn't try to force masculinity on me. I started hrt at age 17 and fully transitioned. I thought all that was normal and couldn't understand late transitioners. It wasn't until I joined this group and started talking to people that I learned my experience was actually quite unusual. I learned that it has only been fairly recently that trans children have been accepted and actually treated with puberty blockers and hrt. Some of the stories I've heard here are heartbreaking. People who had parents try to beat the trans out of them, conversion therapy, electro shock, forced testosterone treatment and being committed to a mental instition. I can certainly understand why these people tried to bury their trans feelings and try so hard to conform. It's so sad. So the argument that you need to have been feminine from an early age to be truly trans is invalid. Unless you are my age or slightly older, if you displayed trans behavior or told people you were trans you most likely would have been subjected to the horrors I just listed. I actually know of only one woman here that was able to transition at a young age during the 60s. Her experience is very rare and unusual.
All you can do is get toxic people out of your life. It doesn't matter what you say or how much you say it, some people will never change their ignorant beliefs about trans people. Period.