tl;dr: Religious abuse only happens because religious leaders are allowed to claim ownership of things other people need in order to live, which is basically the spiritual version of "private property." Because of this, most Internet Atheist criticisms of "religion" would be better directed at capitalism instead.
Content note: Discussion of abusive religion and eating disorders.
From CollectQT's Political Definitions page:
capitalism - An economic system wherein the means of production are largely privately owned. Capitalism is inherently oppressive.
To unpack that a little, "the means of production" are what you need access to in order to make a living. They can be anything from printing presses to app stores to hunting preserves.
In a capitalist economic system, like the ones in China and the United States, these things are all privately owned, meaning that one person or corporation is allowed to control them despite the fact that everyone needs them. This is why capitalism is inherently oppressive; whatever political freedoms you may have, the people who own the means of production have the power to decide whether you live or die, and under what circumstances.
When critics of capitalism are talking about "private property," this is what they are criticizing. The "property" in question is the means of production, not your personal effects. They are not saying that you should be forced to give up your plushies or miniatures. On the other hand, if you've ever seen someone eBay their most prized possessions in order to make next month's rent, you know that this is exactly what capitalism does to the people it makes into losers.
Why capitalism needs losers
Capitalists, meaning people who own the stuff others need in order to live, need there to be scarcity, and the fear of not having enough. If they own one forest, but you can just visit another to collect firewood and hunt game, then owning that forest does them no good. But if they own everything, then you need their permission to do anything.
Some things, by their nature, can't be owned by any one person. They're the things you "can't put a price tag on," like love, friendship, and spirituality. Capitalists do their best to get around this, however, and to ensure you depend on them for those things.
For instance: Through "intellectual property" laws, capitalists can put you in jail just for sharing a song, even if the artist who wrote and performed it would never do that. They can claim exclusive ownership of land, even if it has been understood to belong to everyone (like by First Nations people here in North America) for centuries. And by using advertising, they can scientifically make people want what they're selling by associating good, natural feelings with it, so that you think you'll miss out on those feelings if you do not buy.
If you think you're immune to it, you are wrong. Entire industries, like cosmetics and beauty products, exist largely because advertising has made people believe that they would be miserable without them. So when you make fun of someone's appearance (or even what machine they play video games on), you are working for these companies' owners for free.
Where religion meets advertising
Take a look at this archived page from a few months ago. Look at where they describe "'HeartSell'® - strategic emotional advertising that stimulates response," and who all they say their clients are.
Bonneville Communications is owned by The Corporation of the President of the Church of Jesus Christ of Latter-day Saints, which is the corporation sole that owns the assets and trademarked name of what most people know as "the Mormon church." So in other words, this is a media company owned by the Mormon church, admitting that the warm fuzzy feelings people associate with Mormonism come from advertising.
When I was a Mormon, I thought that Mormon kitsch and official Mormon church publications were pretty much the only way to get that warm, fuzzy feeling, which they call the Spirit and others call frisson. If someone outside the church has it, which I was taught they don't as often, it's to point them at the Mormon church and make them long to be in it.
I was told to be "in the world, but not of it," because The World is a scary place filled with alcohol and drug addicts. They chase empty pleasures, like violent video games and premarital sex, because they don't know the right way to live that makes you feel warm and fuzzy all the time. Except when it doesn't, in which case you need to pray more and be even more Mormon-approved until it does.
So, to recap
Mormon-y stuff is good, everything else is scary. You can find comfort and peace from living a Mormon-y lifestyle, but outside the church there is Darkness and Fear and Despair.
This religious corporation claimed ownership of a feeling and used it to control people's entire lives.
Don't even get me started on their messed-up teachings about sex.
How to really defeat abusive religion
Telling someone who's been in an abusive church all their life that they "don't need God to be happy" is like telling a girl with an eating disorder that she "doesn't need to be thin to be happy." You're fighting against pervasive thought control, that's reinforced through advertising, peer pressure, and a personal sense of inadequacy. They are absolutely convinced that they do need whatever is being sold to them, and they may even be afraid that you will try to take it away.
You can't defeat capitalism like that, whether it has religious trappings or not. What you can do is provide so much abundance that whatever is being held over their head no longer holds value to them. Show them other ways to feel happy and loved, ones that cost less or are naturally free.
This page about treating eating disorders recommends building up someone's self-worth, and helping them learn to trust their own body and feelings over outside pressures and messages. They may need formal treatment and therapy as well, but the goal isn't to make them be "normal" and eat a socially acceptable amount. It's to help them learn what is healthy for them, and to trust and learn to value their self.
This is why abusive religion devalues the self, to the point of telling people they're worth less than dirt. To keep them from doing what's healthy for themselves, so that they'll be broken and always in need of the awful religion.
My personal experience
I was personally horrified, as a Mormon, at therians and otherkin. I thought they were a cult, because I could see they were having real spiritual experiences and I didn't know what could cause that. Even worse, on some level I knew I wanted what they had.
I didn't need to be told what I should want, by Mormons or Internet Atheists or anyone else who thinks they own my life. I just needed to be encouraged. To be shown what I could have if I wanted it, and to not be punished for saying I did.
This is the opposite of creating scarcity, and making people feel afraid they'll miss out if they don't give you money. It's creating abundance, and helping people feel loved and appreciated for who they are.
Only then, I feel, can they truly express themselves, and take the kind of risks that progress and innovation require.