Church

Wherever we see the word of God sincerely preached and heard, wherever we see the sacraments administered according to the institution of Christ, there we cannot have any doubt that the Church of God has some existence, since his promise cannot fail, ‘Where two or three are gathered together in my name, there am I in the midst.’

Calvin: Institution IV 1.9 quoted by Lesslie Newbigin:
The Household of God