(This page will be renamed to "levels of modularity" as it's more accurate.)
Level 0: absolute anti-modularity. It's the claim that religions and worldviews cannot be separated from the broader culture they originated from (or that they are generally associated with). There's also a racist variant of absolute anti-modularity, which claims that religions and worldviews cannot be separated from "races" or "ethnicities".
Level 1: mild modularity. At this level, religions and worldviews can be separated from the culture (or "race/ethnicity") they are associated with, but religions and worldviews themselves are not modular, that is, the ideas/practice contained within them cannot be separated from the religion/worldview itself. At this level, one would argue that a non-Christian cannot validly worship Jesus, or that a non-Muslim cannot validly fast during Ramadan or consider the Qabah to be sacred (perhaps as the home of pre-Islamic arab deities?). That's because at this level, every idea/practice associated with a specific religion/worldview cannot be validly found outside of it.
Level 2: moderate modularity. At this level, ideas/practices associated with a specific religion/worldview can be separated from the religion/worldview itself. That means a non-Christian can validly worship Jesus and that a non-Muslim can validly fast during Ramadan, or that an individual adhering to a non-Dharmic worldview can worship Krishna and have the concept of Brahman in their worldview, or that a non-Scientologist can make use of Scientology practices if so that person wishes. The "catch" is that at this level, each "module" (i.e. idea/practice) must remain unaltered. That means, it's invalid to celebrate Christmas on February 22nd, or to think that we are currently in Dvapara Yuga (rather than in Kali Yuga), or to fast during the month of Ramadan while still drinking water when you're not supposed to.
Level 3: extreme modularity. Same as level 2 but you have absolute freedom. You can validly celebrate Christmas on February 22 etc.
There may be different ways to categorize worldviews. One of those ways (a quite common one) is to regard worldviews as strictly defined packages that contain "beliefs" (which I call "modules"). A common approach is to say that a person can only be considered a "follower/adherent" of a certain worldview at a time (discouraging eclecticism and syncretism). What's more, it seems to often be the case that certain modules are associated with a certain "package" (worldview) and it is considered invalid (or perhaps quirky in a bad way) to adopt that module without adopting the entire package. For example, with this approach, it would be considered invalid for someone to fast during the month of Ramadan, if that person is a liberal panentheistic/polytheistic occultist who is very pro-LGBT, pro-polyamory and praises Prometheus, Satan, Sophia, Hedone, Lucifer and Jesus as the main deities of that person's pantheon, and yet decides to fast during the month of Ramadan. This is because fasting during the month of Ramadan is considered (in this approach) as a module that is exclusively found within the package called "Islam" and cannot be found in any other package. Someone who adopts the "package" approach I've described may say to such an eclectic person "bro, wtf is your religion, why...". This approach discourages eclecticism and syncretism, encouraging following well-defined packages instead. "It's all or nothing". An example of this approach that is common on certain corners of social media is to bundle certain (completely unrelated) attitudes together and call them "left-wing" or "right-wing", and then forcing oneself (and expecting other people) to adhere to the entire package. For example, someone who is pro-LGBT may force oneself to oppose gun ownership, to be pro-abortion, to support Ukraine, to support forced vaccinations, to be an atheist (usually, not always), and to adopt a vaguely corporate, rainbow aesthetics (I may create a page about the relationship between worldviews and aesthetics eventually... this is something rarely talked about). Even if someone does not agree with those ideas, they may adopt them because they're included in the package, and some people don't consider eclecticism as a valid option. This is what I call a "package-focused" approach.
But there are other possible approaches! A module-focused approach (as opposed to a package-focused approach) focuses on modules instead of packages. A person is not labelled or judged based on their adherence to packages, but their adherence to modules. This makes eclecticism a much smoother and intuitive experience. Simple labels are generally not used (e.g. "this person is a [insert worldview word -ist]") is less likely with the module-focused approach. One can say "this person is mostly/a bit/fully/not-at-all [insert worldview], but also mostly/a bit/fully/not-at-all [insert different worldview]", but the worldviews are understood as arbitrary packages of modules packaged in a certain way because of historical contigencies. There may be other approaches too, which I may list in the future.