Yes, it is true that human beings put pen to paper to write the stories we read in the Bible. But, we say, they were inspired by God. We say that God speaks to us through the words of these Scripture authors. We accept this in faith, as it is not something we can prove scientifically.
What is inspiration? The term inspiration comes from the Latin inspirare, meaning "to breathe into." It is the process by which God guided human beings in the composition of the biblical writings so that divine revelation would be communicated through them. Christians believe that God is the divine author of the books of the Bible.
What are the roots of the belief in inspiration? The Israelites believed Moses as mediator communicated God's will to them, the prophets spoke for God, the priests continued the instructional role of Moses while the authors of wisdom literature presented God's gift of wisdom to the people. Judaism developed a firm belief in the divine origin of their sacred books, especially the Pentateuch (first five books of the Bible). Sometimes, inspiration was taken as God dictating the words to the writer so each verse was like a divine oracle.
In the New Testament, there are about 350 Old Testament quotes which show that Jesus and the NT writers believed in the divine origin and authority of the sacred books. Explicit reference is made to inspiration in 2 Timothy 3:16: "All Scripture is inspired by God." Although there is no reference to how inspiration comes about, it seems that some of the early Church thinkers accepted the idea of dictation and during the Middle Ages, it became common.
The New Testament does not claim inspiration for itself but the early Church believed it had Israel's charisma of prophecy which came from God. "No prophecy of Scripture is a matter of one's own interpretation because no prophecy ever came by human will but men and women moved by the Holy Spirit spoke from God" (2 Peter 1:20-21). Early second century Church writings begin to quote the New Testament as being equal to the Old Testament in authority.
The question of how God inspired really came to the fore in the 19th century. Various theories were offered. In 1870, the First Vatican Council declared that all the books of the Bible are considered sacred, although they were written by human writers, because God is their true author and they were inspired by the Holy Spirit.
In 1893, Pope Leo XIII in an encyclical stated that "God so moved the inspired writers and assisted them in their writings so that they correctly conceived, accurately wrote and truthfully expressed all that God intended and only what God intended." Vatican II confirmed this view.
Modern biblical scholarship agrees the biblical books are the result of community reflection and living of their message, that the stories were transmitted orally first and therefore, our way of speaking of books and writing is limited. In a manner of speaking, Israel and the Church were the authors of the New and Old Testament, respectively, since the writers were spokespersons for the experience of their religious milieu.
A term related to inspiration is inerrancy which means that the Bible cannot be in fundamental error since it comes from God. This does not mean that references of the Biblical authors related to "scientific" or "historic" data are free from error for their intention was not to explain science nor to write history as we know it. Nor does this mean that the human writers could not make mistakes, but rather that their human limitations did not hinder the expression of God's revelation in Scripture.
When we talk about inspiration, we mean God guided the authors in the message they give us. The words of the Bible are true in the sense the human author gives them and so we must understand them in that sense. They used their own gifts and talents and styles of writing as we can clearly see when we read the Gospels.
For us to understand, we must study the mindset as well as the language usage of that period and in that part of the world. We need to understand literary forms and the style of each writer. That is the work of Scripture scholars.
The Catechism of the Catholic Church points out that the process of inspiration, in a way, continues in our day as Christianity is a religion of the Incarnate and Living Word of God. The Scriptures (both testaments) were born in living and dynamic communities. They are not dead entities of a long time ago. They are living realities for us today.
They are the living word of God which opens our minds to the Spirit so that we can understand them and live with one another in the God of love they reveal.
My friends say that the Bible was written by men so how can we say it's from God.