The catholicity of the church is known by these marks:
The Holy ministry headed by the faithful ministers of the Word.
The Holy liturgy as has come down to us through the ages. The so-called contemporary - that I only compare with the spontaneous fashions in ladies dresses that appear in the market almost every six or even four months in Kenya - deviates from it.
The pure preaching of the Word – Law and Gospel.
You can read the whole of it here.