Historically, the term refers to the whole Christian church in the era of the Twelve Apostles or to any of the ancient local churches founded by one of the Apostles. In theology, the term means a church faithful to the beliefs of the original Apostles and/or linked to them through historical continuity. A number of denominations use this as part of their title, but they are often quite different from one another. Be certain which “apostolic” church you are dealing with. Lowercase unless part of an official title.