But how do we even know what is the written Word of God without the authority of the Church to certify it? On what authority did Martin Luther remove seven books of the Old Testament (and attempted to remove seven books from the New Testament) that the Church had certified as Sacred Scripture for over one thousand years?
Additionally, Scripture (see Acts 15) testifies itself that the gathered Apostles and presbyters of the Church speak with the authority of the Holy Spirit. If that authority existed once, and Scripture cannot be denied, then it exists today. Moreover, the Bible shows that Paul gave Timothy and Titus, as well as those appointed by them, the mandate to preach the Gospel before the New Testament was even completed. How could they have done so if there were limited to what was written down? All that your biblical reference do is deny the private interpretation of Scripture, something that the Protestants are guilty of, not Catholics.
If Christians have disputes about the faith then they should follow the example found in Acts 15 and submit it to the rightful pastors of the Church rather than insist on their own private judgment as those who go “without any mandate from us [the Apostles and presbyters] have upset you with their teachings and disturb your peace of mind.” This is the way of the Bible, not private interpretation.