Why do Christians use the Bible as an authority in our lives? The Bible is a credible source of authority because of its historical and textual reliability in addition to the reliability of God's promises and the unity and cohesion of the story it tells over 1000+ years. Alone, these should be reasons enough for it's place in our lives, but even more it are the claims that that Bible makes about itself from the psalmists to the authors of the New Testament letters and even Jesus himself. God's word, should have a say in how we live our lives.