A place or structure in the home reserved for religious ritual or prayer; in Christian use, frequently used in figurative contexts relating to family prayers.
family altar/ˌfam(ɪ)li ˈɔːltə/ /ˌfam(ə)li ˈɔːltə/ /ˌfam(ɪ)li ˈɒltə/
Late 17th century; earliest use found in Oliver Heywood (bap. 1630, d. 1702), clergyman and ejected minister. From family + altar.