Narkissos,
But you must continue in the things which you have learned and been assured of, knowing from whom you have learned them, and that from childhood you have known the Holy Scriptures, which are able to make you wise for salvation through faith which is in Christ Jesus. All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness, that the man of God may be complete, thoroughly equipped for every good work. (2 Tim 3:14-17 NKJV)
And thou -- be remaining in the things which thou didst learn and wast entrusted with, having known from whom thou didst learn, and because from a babe the Holy Writings thou hast known, which are able to make thee wise -- to salvation, through faith that [is] in Christ Jesus; every Writing [is] God-breathed, and profitable for teaching, for conviction, for setting aright, for instruction that [is] in righteousness, that the man of God may be fitted -- for every good work having been completed. (2 Tim 3:14-17 Literal Translation)
You cannot take the second verse containing the phrase "every writing" out of context. In the context of the passage, Paul is clearly speaking of the Holy Writings indicated in verse 15. The "Writings" in verse 16 are God-breathed (inspired by God) which makes them Holy and infallible since God is Holy. It is obvious that Paul is speaking of the Holy Scriptures here. God would not lead His children to some other "writings" other than His Holy Word for doctrine, for reproof, for correction, and for instruction in righteousness. (This is not to say that there are not writings or books in existence which have been written by holy men of God, that are beneficial for us and that contain truth within their pages - they do exist).
Leolaia's two posts are far too long for me to go through right now. Sorry.