The term gay used to mean happy and a prostitute. It's modern meaning is 20th century and yet it is listed by your online dictionary as 14th century.
gay - Definition from the Merriam-Webster Online Dictionary
1gay Listen to the pronunciation of 1gay
Middle English, from Anglo-French gai, of Germanic origin; akin to Old High German gāhi quick, sudden
1 a: happily excited : merry <in a gay mood> b: keenly alive and exuberant : having or inducing high spirits <a bird's gay spring song>2 a: bright , lively <gay sunny meadows> b: brilliant in color3: given to social pleasures ; also : licentious4 a: homosexual <gay men> b: of, relating to, or used by homosexuals <the gay rights movement> <a gay bar>
Except of course that according to your very definition it means that in a religious context.Not to mention that the TERM "established church" was not ever used in the 1st amendment.