Written from a Roman Catholic understanding but this would also be shared by Orthodox. Hat tip to N. Begley.
“Some non-Catholic Christians urge that the whole Church went off the rails by about A.D. 95, and hence that ‘Church history’ is really the record of an immense botch. These Christians would urge that the Church of Jesus Christ, made up as she is exclusively of true believers, pursued its humble and obscure way in little assemblies here and remote groupings there, quite apart from the brontosaurian impostor that, early on, took unto herself the name of The Catholic Church.
The difficulty of maintaining this view arises from the nature of the topic itself. The Christian believers who were under the authority of the apostles and then under the bishops appointed by them understood this episcopal entity to be the Church. All the writings we have from the first and second century attest to this. If we will read the letters, sermons, and tracts of Ignatius and Clement and Justin and Irenaeus, we will find a church that, if she is not the Church, is certainly the only one anyone had any knowledge of. If we wish to forego any connection with this lineage, then we find ourselves obliged either to link ourselves with the Montanists, the Marcionites, or the Nicolaitans or to postulate some fugitive network of assemblies of which there is no record.”
(Thomas Howard, On Being Catholic, San Francisco, Ignatius Press, 1997, p.50-51). Paul Newcombe
The Beautiful Path 