>>1) Where did Jesus give instructions that the Christian faith should be based exclusively on a book?<<
In John 14:26 Jesus inspired the Apostles with His Word. John 14:26, “But the Comforter, even the Holy Spirit, whom the Father will send in my name, he shall teach you all things, and bring to your remembrance all that I said unto you.” (ASV) Jesus said that the Holy Spirit would be given so that the Apostles will have brought to their remembrance all that Jesus taught, i.e., Jesus wants to pass on to the world through the Apostles not their wisdom, not their insight, but His own Word! Jesus, remember, is the high point of God’s revelation. Jesus turns to the Apostles and says, “The Spirit will bring to your mind everything that I have taught.” He didn’t say that to any of the people after the apostles did he.
In Matthew 10:40, Jesus explains the concept of an apostle known well in that day when He said, “He who receives you receives Me, and he who receives Me receives Him who sent Me.” (NKJV) Jesus was sent by the Father, and Jesus turns and sends the Apostles into the world. And He says “the person who receives you (as My apostle) in fact receives Me; and in so doing, receives the Father Who sent Me!” Jesus made the apostles spokesmen for Him and authorized to speak His word. They didn’t speak their own words but through the Holy Spirit remembered everything Jesus spoke. Jesus didn’t give that authority to anyone else did He.
Paul taught that it was his word. Galatians 1:11-12, “For I make known to you, brethren, as touching the gospel which was preached by me, that it is not after man. For neither did I receive it from man, nor was I taught it, but it came to me through revelation of Jesus Christ.” Once again, no other human beings were given that promise by Christ.
Paul says II Timothy 1:13, Paul says, “Hold the pattern of sound words which thou hast heard from me, in faith and love which is in Christ Jesus. That good thing which was committed unto thee guard through the Holy Spirit which dwelleth in us.” You see he says to listen to those who were told that the Holy Spirit “which dwelleth in us” is what we are to “hold to”. No one else was told that the Holy Spirit would “teach you all things and bring to your remembrance” did He.
The apostles wrote what the Holy Spirit guided them to write and we know that Jesus told them the Holy Spirit would “bring to their remembrance” what to teach. Did Jesus give that promise to anyone else? Did the apostles promise anyone that the Holy Spirit would “bring to their remembrance” what Jesus taught? Paul warned about teaching what he didn’t teach. II Timothy 1:13, Paul says, “Hold the pattern of sound words which thou hast heard from me, in faith and love which is in Christ Jesus. That good thing which was committed unto thee guard through the Holy Spirit which dwelleth in us.” The only teaching we have from the apostles is recorded in their writings. What was important to know was written down and not left to the risky word of mouth.
Once again Jesus says. John 16:12-15 12"I still have many things to say to you, but you cannot bear them now. 13When the Spirit of truth comes, he will guide you into all the truth, for he will not speak on his own authority, but whatever he hears he will speak, and he will declare to you the things that are to come. 14He will glorify me, for he will take what is mine and declare it to you. 15 All that the Father has is mine; therefore I said that he will take what is mine and declare it to you.
No other human was given that promise by Jesus and the writings they left us are all we can truly say with faith are inspired by the Holy Spirit and as we see in II Timothy 1 we are warned that we should listen to only what the apostles taught.
The RCC, John Smith, and Muhammad might convince you that they somehow can add to what we know the apostles taught but I’ll stay convinced that Jesus told the apostles that the Holy Spirit would “bring to their remembrance” and told no one else that.
"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 PERFECT, THOROUGHLY FURNISHED unto all good works." 2 Tim. 3:16-17.
All Scripture—meaning what? You are dancing around the plain fact that the books of the canon were not inscribed on tablets of stone as was the law of Moses direct from the hand of God. Why these writings? Why ONLY these writings?