Without mentioning the details of early church “fathers” and early manuscript collections that affirm the 27-book collection to have existed before the 4th century, the Bible overwhelming shows that the Apostles oversaw the collection of the New Testament writings. Paul instructed the sharing of His writings in Colossians 4:16, and warned against false writings in 2 Thessalonians 2:1–2 and 3:17.
In short, 2 Peter 3:16 shows that all of Paul’s epistles were collected as Scripture and spread into lands not specifically addressed. Paul quoted Luke 10:7 as “Scripture” along with Deuteronomy in 1 Timothy 5:18. With the Gospel of Luke confirmed as Scripture, then the book of Acts is certainly Scripture along with the written Gospels mentioned by Luke in Luke 1:1–3 are too. Second Peter 1:16–21 shows that the writings of the Apostle John and Peter were already Scripture. John also affirmed inspired Scripture written by the Apostles in 1 John 1:1–4. The Apostles did oversee the collection. Read more here “The Formation of the New Testament.”
Some false teachers will affirm the inspiration of the Scriptures, and yet undermine the authority of the Scriptures by teaching that the New Testament Scriptures were collected in a 4th century council. These teachers would have you believe that the writings of the New Testament were not intended for all Christians.
Many false teachers even many conservative assume that men gathered the New Testament together in the 4th century, and many of them would even hide this belief from their fellowship. From this presumption, some say that 1 and 2 Timothy and Titus are not inspired or even written by Paul. Some may refer to Clement of Rome’s letter to the Corinthians or to other spurious “gospels” written in other centuries as though these have been cut out while never added or inspired in the first place. Such is bias. Many simply want to encourage doubt to persuade people to be cynical towards the reliability of even Jesus’s own words. This doubt undermines the infallibility of Christ, God’s providence in preserving Scripture, and denies that the Bible is complete in beliefs and practices. This allows the false teachers to assume an authority that is not theirs.
Such doubt disregards God and His ability to providentially sustain the words of Christ especially those words given to the Apostles and prophets. There is nowhere else to find Jesus’ words but in the Bible. Jesus said that His words will never pass away (Matt 24:35; Mark 13:31; Luke 21:33). Do not doubt that the most profound and sublime words ever written are in pristine and pure order being preserved by God.