This is the most basic question of the faith. It should be as simple as saying, the Bible is the Word of God. But today many deny this, and most are moving away from Scripture as the sole source and norm of Christian teaching.
You might think this started in recent times, but in reality it has its roots in the middle Ages. In Roman Catholicism, the sole source and norm of doctrine is not Holy Scripture but in reality the Ego of the Pope, who "boasts that all rights exist in the shrine of his heart." In the Papacy only so much of Scripture is regarded as binding as the Pope approves and confirms.
The incredible thing is that today most of "Protestantism" has become what they protested in the first place. Instead of having the Pope's heart determine doctrine, they use their own heart as the source and judge of Christian teaching. They deny that the Holy Scriptures are the Word of God and set themselves up as popes ready to determine doctrine for themselves.
This was and remains one of the Great SOLAS of the Reformation - the Great "Alone" Statements upon which Luther returned to the teaching of the Apostles. Christian teaching comes from the Holy Scriptures alone. God will not speak to us outside of them. He has not given us another way of understanding His revealed will. They are true. Reliable. Inspired. Inerrant. Eternal. Authoritative. Efficacious. Perfect. Sufficient for Salvation. Clear.
Without them we are grasping in the dark. Without them we are alone. We are lost. But God has kept them for us. He has preserved them for us. We do not shape them - they shape us - call us - save us. And God is pleased to give them to us for free.
Never take the Holy Scriptures for granted. They are worth more than every treasure in the entire universe, yet they sit on your kitchen table, your bedside table. Dive in. Ask questions. But know that when you read or hear these words, God is speaking them to you.