ideology
totemism
Creed. (Also, a five letter word for a set of beliefs beginning with "d" is dogma).
creed, credo
The word is credo.
One food ending in Y is chicken curry
yummy
Some three letter words ending in Y are:anybaybuycaycoycrydaydryfryflygayguyhayheyjayjoykeylaymaypayraysaysoyshyslyspystywaywhywry
religion? Religion is not a word for a set of beliefs but a word for a set of beliefs that explain existence as well as meaning to the universe. Ideology is probably the closest word that explains a set of beliefs probably.
A statement or set of beliefs is sometimes called a creed or a confession.
The analogous word for trip ending with the vowel y could be journey.
A set X is called a proper subset of a set Y if X is contained in Y but not equal to Y.
Examples of nouns ending in -y that is preceded by a vowel:alleyboycaychimneydaydonkeyessayjoykeymonkeyplaytoyturkeyvalleyway