Historical Baptists have held to distinguishing marks of faith and practice, including that the Bible is the final authority for faith and practice. As NT believers, who hold the completed Word of God in our hands, we look to the NT and to the OT for guidance in what to believe and how to live. But what did saints of God do in the OT? The same thing.
We find an example of this in Esther 4:16, where Esther says, “And if I perish, I perish.” Her statement strikingly resounds what Jacob said in Genesis 43:14, “And if I be bereaved of my children, I am bereaved.” The contexts resemble each other: each person faced a dire situation, yet each trusted the providence of God.
What does this teach us? The saints in the OT had the Word of God available to them, and they knew what it said. They studied it, learned it, and taught it to the next generation. They identified the principles in given passages and applied them to their circumstances. In other words, they lived by every word that proceedeth from the mouth of God (Dt. 8:3; Mt. 4:4).
When we go through life living according to the Word of God—understanding it, teaching it, and applying it—we follow the pattern of what believers have done through the ages, including saints in the OT.