5) That Orthodoxy is a church .
Orthodox is not a church .
Orthodox is not a church as they do not preach the gospel. God says in the bible the city of Rome is the "Mother of Harlots" and describes its connection to Catholicism, in chapter 17 and chapter 18. A mother has daughters, and it is clear the Orthodox church (that proudly tells the world her own roots in the Roman Empire) is a daughter of the Mother of Harlots. not a church at all.
One Church .
Protestants have one church - all those born again.
Denomination is rooted in de "formally" and nominate "named". The new testaments has formally named churches, "the church in Ephesus" etc, named formally to distinguish it. All Catholic and Orthodox churches are wrong, as they accept Jesus as a Semi Saviour. At least some Protestant denominations have the right gospel, do not kill, or remarry (two of the big sins defiling all churches everywhere). If "narrow is the way" is true (and it is) that excludes Catholics anyway.