I would like to develop this argument at some time in the future, but hope to have it sharpened here in the meantime.
As Protestants (specifically of the Evangelical persuasion) who are all friendly to Thomism, this is a topic upon which we simply do not agree with our Roman friends – and should therefore develop arguments for and against: I hold Scripture to be authoritative *in itself* (as in its authority is recognized) while my Roman friends hold that it is, of course, authoritative based upon the authority of the Church (it is discovered to be authoritative vs. it is declared to be authoritative) . Therefore:
The statement “All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, so that the servant of God may be thoroughly equipped for every good work” – is either true or false. For sake of argument, let us all say that this is true.
1) All which is ‘God-Breathed’ must, by virtue of its origin, be authoritative within its own nature**
2) All Scripture is God-Breathed (per Timothy)
3) Therefore, Scripture must, by virtue of its origin, be authoritative within its own nature.
If Scripture is “God-Breathed” then it, by definition, cannot be *under* the authority – or given authority – by the Roman Church, but must be *recognized* to have its own authority by virtue of Who Spoke it (God-Breathed); which is the evangelical position.
**As opposed to someone/something else ‘giving’ it authority.