I think the OP’s question is a difficult one to answer.
First of all there’s the issue of having a simple, coherent definition of religion that differentiates it from other collectively shared ultimate (value making and corresponding moral judgment-measuring) “philosophies/purposes of life”.
I understand Xunzian’s logic in including Communism, as it sums up every communicable thing (of “reality”/“life”/whatev) as an expression of an ultimate, all-encompassing abstract (in this case I’ll say “conflict”), when it itself is not material (not a thing that actually has a physical effect on anything), but only has meaning with a circular explanation of at least two things “being in conflict”
–indeed, when read ontologically, “materialism”'s emphasis on matter preceding thought, and declaration that the world
(or the universe or any word referring to any and all subjective experiences of an environment that a group of people would agree “objectively exists”)
is material ,
(when “the world” is not material, but rather an unspecified collection of forms and relationships between them that have never been even really been cognizable, as they’ve never NOT been–“the world” is practically synonymous with the “thought” required to make it “real”),
appears ridiculous…something like:
The abstracted, thought-dependent “Material” that only has meaning–only exists and affects “the material”–in thought is the ultimate reality
–even though reality is also just an abstract in thought that refers to the common backdrops of all thoughts, IE thought, or thinking, itself;
matter precedes thought, and is more real than thought, though the issue or question of anything being (real) at all is dependent on a symbolic thinking mind that only sees (constructs, interprets, makes) “an existing material world” according to metaphysical thought-blocks.
HOWEVER–and I admit I haven’t read the communist manifesto, nor any of Lenin’s writings to an extent I feel confident in his worldviews beyond the sociological applications of the common ideas historically attached to his name–
I think that, even though Dialectic Materialism’s principles are written in such a way they’re (in meeting the standards of a communicable language, necessarily) relating and equating physical objects and metaphysical abstracts with words like “is” (leaving it open to ontological interpretations), it was intended as an epistemological theory, practically based on relating to and manipulating the things one sees in effort to overcome and avoid distasteful subjective experiences that can be pretty quickly described and understood according to the interaction of concrete things.
I mean… ask a communist to explain what conflict is, and how his belief system tries to harmonize with it. If he is intelligent at all he’ll identify the subjective feeling of conflict with certain physical situations/interactions in such a way you’ll agree it’s real in the sense it describes a feeling you’ve experienced, that is attributed to that “conflict” between you and physical things/relationships. You may not become an advocate for communism yourself, but you’ll at least understand them and communicate about the things with an understanding of what they refer to. Now ask a Christian what the holy spirit is, and why you should accept it as true and let it into your life. How likely is it he’ll say something like "It’s a word that refers to a certain feeling of collective oneness, and personal acceptance, that I get when I am in church and my voice, rather than holding the whole world on its shoulders, becomes but one string in a symphony; the holy spirit is an ocean of cathartic release that pulls me in and makes me it’s own–it’s the gentle, invigorating release of any worry about being a lonely, misunderstood wave.
My point is, if we’re going to call that (as I understand it and have described it) religious thinking, what kind of moral-interpreting belief system isn’t religious? I see the OP as being more specific than “What collective value-system philosophy is best?”