The word Church can be used as a noun or adjective. Church is used as a noun in the sense of church in the Church of Cognizance. In this use it implies "a congregation" or "membership", "a body of believers" with "shared practices"!
1.) noun: Those who accept and practice a particular religious belief: communion, denomination, faith, persuasion, sect. See religion
2.) adjective: Of or relating to a church or to an established religion: churchly, ecclesiastical, religious, spiritual. See religion