ephemeral, transitory

religious (committed to the practice of religion)

voluntary, of one's own initiative, of one's own accord

perpetual, permanent, everlasting

modern

secondary

“a hundred days of sermonizing, one fart” → a metaphor for how something that one has put great effort into can come to nothing after even a slight mistake, much as a hundred days of serious spiritual study can be lost to the winds

(chiefly Internet slang) thinking with common sense

Kyūjitai form of 初歩的

(linguistics) diachronic