One cannot be a Christian, or even get an essential grasp of Christianity, without giving a definitive answer to whether Christianity is essentially determined to a particular sect. It is now commonly accepted that Christianity is not essentially determined to one sect.
If Christianity is essentially determined to one sect, then whoever is not a part of that one sect is essentially unchristian. It is perhaps out of a feeling of tolerance or niceness or fear of sectarian division we tend to all adopt the opinion that Chirstianity is not determined to one sect.
But if Christianity is not determined to one sect, then clearly one not need be a member of any sect to be Christian, and further one need not believe anything that is peculiar to a particular sect, nor follow any of its rules. Even if there were something common to more than one sect, a person could still judge it to belong to “institutional” Christianity, and therefore judge that he need not follow it.
And so if we believe Christianity is not essentially determined to one sect, we are forced to believe that true Christianity is found in individualized Christianity, as opposed to institutional Christianity. Individualized Christianity means that the individual gets to determine the observances and doctrines.