2 Timothy 3:
13 But evil men and impostors will grow worse and worse, deceiving and being deceived. 14 But you must continue in the things which you have learned and been assured of, knowing from whom you have learned them, 15 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.
16 All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness, 17 that the man of God may be complete, thoroughly equipped for every good work.
2 Timothy 4:
4 I charge you therefore before God and the Lord Jesus Christ, who will judge the living and the dead at His appearing and His kingdom: 2 Preach the word! Be ready in season and out of season. Convince, rebuke, exhort, with all longsuffering and teaching. 3 For the time will come when they will not endure sound doctrine, but according to their own desires, because they have itching ears, they will heap up for themselves teachers; 4 and they will turn their ears away from the truth, and be turned aside to fables. 5 But you be watchful in all things, endure afflictions, do the work of an evangelist, fulfill your ministry.
Scriptures are not man's authority, but God's:
2 Peter 1:
16 For we did not follow cunningly devised fables when we made known to you the power and coming of our Lord Jesus Christ, but were eyewitnesses of His majesty. 17 For He received from God the Father honor and glory when such a voice came to Him from the Excellent Glory: “This is My beloved Son, in whom I am well pleased.” 18 And we heard this voice which came from heaven when we were with Him on the holy mountain.
19 And so we have the prophetic word confirmed, which you do well to heed as a light that shines in a dark place, until the day dawns and the morning star rises in your hearts; 20 knowing this first, that no prophecy of Scripture is of any private interpretation, 21 for prophecy never came by the will of man, but holy men of God spoke as they were moved by the Holy Spirit.
2 Peter 3:
14 Therefore, beloved, looking forward to these things, be diligent to be found by Him in peace, without spot and blameless; 15 and consider that the longsuffering of our Lord is salvation—as also our beloved brother Paul, according to the wisdom given to him, has written to you, 16 as also in all his epistles, speaking in them of these things, in which are some things hard to understand, which untaught and unstable people twist to their own destruction, as they do also the rest of the Scriptures.
Just a sample. No man, no organization, no self-proclaimed church magesterium gets to decide what is or is not God's Word. See the comments of Peter above.
That’s all well and good... but it doesn’t give even a hint as to how specific books were accepted or rejected from the Canon of Scripture.
One can’t ask Scripture to tell you what books of Scripture to include... since the very Scripture you ask might not be Scripture! For example: you (as a non-Catholic) would likely not consult 2 Maccabees to find out if any other book is genuine... correct? But why not? If 2 Maccabees contradicts Luke (it doesn’t, BTW), then logic would not be able to decide between the two; is 2 Maccabees false because it contradicts Luke, or is Luke false because it contradicts 2 Maccabees?
Again: it’s all well and good to have a sentimental attachment to a given canon of Scripture; but logic is rather ruthless—it doesn’t CARE whether we “like” (or even love) the tradition or person who gave us the original collection of books. Logic is concerned only with clear definitions, true premises, and valid conclusions which follow from those premises. So... aside from the fact that you inherited the 66-book canon from Luther (and other 16th-century people), how do you prove that your collection is the correct one?
(N.B. Please, I beg of you: before you ask me how the Catholic Church proves its own canon—and I’ll address that later, if you like—please answer this question first. Anything less would be a mere appeal to “tu quoque”, which is a textbook fallacy; pointing out the allegedly leaky boat of your neighbor won’t stop your own boat from sinking.)