Well, it might seem that way sometimes. But in the end, what's different to religion is that this is all rooted in facts. Facts which are quite abstract, so not everyone gets them and even those who do get them sometimes wonder whether it's important or not sometimes. The thing is, Linux is at its core a neutral, open and free operating system, and it's basically the only one which is advanced or mature enough to be a real competitor to let's say Windows or MacOS. Of course it's more than a competitor on the server, it's basically the only relevant server operating system (Windows Server has a niche in application servers within a MS intranet domain, or to control Windows clients via policies, that's about it, and MacOS server is already long dead I think). Of course, some of Linux' success is because those same companies also contribute a lot to the development of Linux, because they need it for themselves as well. But that's just one more thing which makes Linux a very unique thing. It's like a neutral baseline for an operating system. Like a very capable OS core that everyone works on, even the competition works on it, because they also rely on it.

That it's open source and transparent and that anyone can use it or improve it or change it or whatever makes it special, because it's not a commercial black-box product where you just consume it as-is and have zero rights whatsoever to do or change anything about it. That's actually incredibly special in today's commercialized landscape. Its open nature also means it can never die, only grow. And because it's a proven good system which is also so very different compared to established desktop OSses, it can happen that its users or fans can seem somewhat religious towards it. But, again, compared to religion, religion is based on pure belief (otherwise it would be called fact). There's nothing religious about Linux or open source software. It's simply a special operating system, and not in a bad way at all. And closely related to it is, of course, the whole free/open source software movement. Which every user, even those of closed operating systems, can and do benefit from.

And since today's commercial software continues growing more and more user hostile (ads, spying, bloat, dark patterns, high prices/software rental models), it's getting increasingly important to have at least the option of a true alternative. Even users who absolutely hate Linux and open source software should be glad that alternatives do exist, so that once the food they are being fed by Microsoft and so on doesn't taste good anymore, they at least have an option to switch to something else entirely.