Everything else is simply not "a religion." And I also have a whole book to cite:
"Faith Versus Fact: Why Science and Religion Are Incompatible" by Jerry A. Coyne
"Evolutionary biologist Jerry A. Coyne lays out in clear, dispassionate detail why the toolkit of science, based on reason and empirical study, is reliable, while that of religion—including faith, dogma, and revelation—leads to incorrect, untestable, or conflicting conclusions."
Also, Merriam-Webster Dictionary:
"Definition of religion
1a : the state of a religious (e.g. "a nun in her 20th year of religion")
1b(1) : the service and worship of God or the supernatural
1b(2) : commitment or devotion to religious faith or observance
2 : a personal set or institutionalized system of religious attitudes, beliefs, and practices
3 archaic : scrupulous conformity : conscientiousness
4 : a cause, principle, or system of beliefs held to with ardor and faith"
If you think "4" fits with the bad attempt to redefine the real meaning, it in to explain the use in the sentence like "rock'n'roll is his religion."