I think some of this is true and some is not necessarily true. You can believe all spirits are dangerous and not necessarily believe all the stories the Dalish have are true. Their beliefs may have slants based on the information they were given, but when speaking of spirits we've reached a different level of belief. Spirits are something we very well know exist. You can't really deny they do. You basically have to have some impression of their nature. Being raised Andrastrian doesn't mean your view has to remain as "good spirits/bad demons", especially if you have any experience at all with them. An Adrastrian raised person could pretty easily come to the conclusion that all fade creatures are potentially dangerous based on their experience with fade creatures. They're widely available, even more so now that the veil is ripped.
I was addressing the nuances of how the Dalish don't share the same views as Andrastians about the Fade (the Beyond) and Spirits and Demons (spirits), which we know about from conversations between Merrill and Anders:
Act I -
Anders: Maybe you don't really understand the difference between spirits and demons.
Merrill: Did I ask you?
Anders: Spirits were the first children of the Maker, but He turned his back on them to dote on His mortal creations. The ones who resented this became demons, driven to take everything mortals had and gain back the Maker's favor.
Merrill: Your "Maker" is a story you humans use to explain the world. We have our own stories. I don't need to borrow yours.
Act II -
Anders: Do Dalish honestly not recognize the difference between demons and beneficial spirits?
Merrill: We've never thought of the Fade as the home of our gods. It is another realm, another people's home. No different or more foreign than, say, Orzammar.
Varric: You can say that again.
Anders: But have you never studied the types of demons? They break down very clearly into different sins--
Merrill: Spirits differ from each other, just as you and Hawke and Isabela are all human. More or less...
That's basically the difference between being Andrastrian raised and Dalish raised. There are basically no elements that are inherent to all Andrastrian raised people that don't necessarily believe the religion is right, because nationality takes so much precedent, but almost all Dalish people have a huge amount of common cultural norms, regardless of whether they see the religion as literal or not.
I agree with you that people can differ on their views despite their upbringing, but I don't see why an elf would continue to be Dalish if they didn't want to be Dalish anymore. Velanna, Arianni, Merrill, and others have voluntarily left their respective clans to go their own way. Being Dalish, and remaining true to the elven culture and religion, is part of their society. That's the Dalish: "Until then, we wait, we keep to the wild border lands, we raise halla and build aravels and present a moving target to the humans around us. We try to keep hold of the old ways, to relearn what was forgotten."
That's what marks the difference between the Dalish and the myriad of Alienage elves across Thedas, all from different human cultures, or even the Qunari elves: keeping true to the ways of the Elvhen.