We are the church.
Denominations are not the church.
The church, the Body of Christ, is an organism, not an organization.
Loyalty should be to the Head, which is Christ, not to denominations. Denominations can’t save. Christ does.
Denominations (or Communions, so as to include the non-Protestant groups) are the Church. One particular Communion may not be able to say that it, and it alone, is the Church--but no particular Communion is without some claim to being part of the one, holy, catholic and apostolic Church.