How important is the Bible?

Your principles have been the music of my life throughout the years of my pilgrimage. I reflect at night on who you are, O Lord, and I obey your law because of this.
Psalm 119:54-55 NLT

The testimony of presidents
The Bible was clearly important to many American presidents.
A few examples:

It is impossible to govern the world without God and the Bible.
George Washington

The whole inspiration of our civilization springs from the teachings of Christ and the lessons of the prophets. To read the Bible for these fundamentals is a necessity of American life.
Herbert Hoover

In regard to this great book, I have but to say, it is the best gift God has given to man. All the good Savior gave to the world was communicated through this book. But for it we could not know right from wrong. All things most desirable for man's welfare, here and hereafter, are to found portrayed in it.
Abraham Lincoln

Hold fast to the Bible as the sheet-anchor of your liberties; write its precepts in your hearts and practice them in your lives. To the influence of this book we are indebted for all the progress made in true civilization, and to this we must look as our guide in the future. Righteousness exalteth a nation; but sin is a reproach to any people.
Ulysses S. Grant

From Great Thoughts & Funny Sayings by Bob Phillips (Tyndale House), pp 39-40