Is it normal it's funny that people will lose respect for someone over dumb things

I do find it odd how so many people have such a sensitive "You're dead to me!" trigger these days. I wonder if that's yet another malign effect of social media: people feel they have so many "friends" online that they're far more willing to trash real world friends than they were back when social circles were much more limited.

All four of the specific things you mention are politically charged these days in the USA. They tend to be indicators of a specific mindset, and people like to hang out with those who agree with them more than they enjoy being with those who constantly challenge their opinions and prejudices; thinking is hard, and it's easier to see the world in black and white terms rather than try to deal with all the shades of grey.

What I do find peculiar is how you seem to be saying that the people who have "unfriended" you have all known who you are as a person - rather than just as a stereotype based on your atheism, attitudes towards the vaccine, sexuality or whatever - but you increasing their knowledge of your opinions by one little thing resulted in them dumping you. Maybe this is just due to cognitive dissonance sometimes being almost physically painful. But then we all have our red lines. I can easily imagine my opinion about someone changing drastically if they were to suddenly casually say something grossly racist, mention that they believe all women who are raped were asking for it, or express some other opinion I found vile and disgusting.

Unfortunately, there are people who can't seem to tolerate any beliefs different from their own. I get it with certain things that cross the line (such as the way people treat each other, kids, animals, etc.), but not with minor things. It's great that you are able to be reasonable, though!

Edit: Sorry, I accidentally hit send to soon!

I stopped contacting a friend when I found out that he declawed his cat, and thought declawing was an acceptable thing. It was just such a turnoff for me.

Personally I couldn't give a twat what people think of I like the person ill hang with them. You could tell me you look at underage porn I'd be like ok keep that shit to yourself. So you seen the new transformers movie?

People are weird man. The key if you hate certain topics is just dont bring them up. If they will rile you up to that point and it comes up just don't talk about it. As adults we all need to learn this lesson.

Only one of those I understand which is guns. I personally don't befriend any who are pro guns because it means they lack common sense which scares me so I steer clear of them but I would never outright say it was the reason for me not continuing a friendship because I'm not the kind of person who lashes out at someone for believing something different. However I don't understand how they can not know if they're your friend. Surely that's something that would have come up in conversation before. I know all my friends are opposed to guns and I've known that about them for many years so if they already knew you were pro gun and didn't support you a while ago it's odd for them to suddenly want to end the friendship now.

And for the vaccine and coming out as bi, that's just ridiculous to me and definitely not normal for them to abandon a friendship over.

What's dumb to you is not dumb to others; that's ultimately the answer here.
You think religion is unimportant; your anti-theist friend disagrees. You think getting vaccinated is fine; your anti-vax friend disagrees. You think bisexuality is acceptable; many people greatly disagree. You think guns are useful tools for protection of homes; many people disagree.
You think these are small, but to other people these are very important topics.

Not normal. I dont know where you live but I dont feel that is a normal trait in people.