Poeple may follow what ever prophet/vicar/synod/temple etc but as for myself I will try to follow Testament of Jesus Christ.
” Dear friends, although I was very eager to write to you about the salvation we share, I felt compelled to write and urge you to contend for the faith that was once for all entrusted to God’s holy people “ Jude
And how do you know that the Testament is complete? It does not tell you how many books it has. The Church does.