Sometimes I’ll ask my kids, “Are you ready to go to school?” “Yep,” they will reply. Then I will look at their feet and say, “Where are your shoes?” “Oops!” This is a case of not being thoroughly equipped.
In 2Timothy 3:16 we see the apostle Paul telling Timothy the importance of the holy scriptures and how they allow the man of God to be perfect and thoroughly furnished. In verse 10 Paul has already mentioned that Timothy fully knows Paul’s doctrine, manner of life, purpose, faith, etc. Timothy needs these things in addition to having the holy scriptures (which, in Timothy’s case, would only be the Old Testament scriptures since the entire Bible was not even written yet).
Paul is not telling Timothy that the Bible is to be his sole authority. Paul’s message is that the scriptures are an important part of a complete set of equipment. Timothy needs the scriptures, but not without knowing Paul’s doctrine, manner of life, purpose, faith, etc. Timothy does not need the scriptures “alone.” This would be like telling my kids that they are fully equipped to go to school wearing only their shoes and nothing else.
Christians are not fully equipped with only a Bible (sola scriptura). We also require legitimate, apostolic teaching authority, proper manner of life, understanding of purpose, correct understanding of the faith, etc. These things are found in the Church that Christ established and continues to sustain through apostolic succession and the Holy Spirit. As Timothy needed Paul, we need the Church. Not just “any” church, but the One, Holy, Catholic and Apostolic Church.