Sometimes we don’t realize how big of a deal it is that God’s voice is in the Bible! God’s voice has been written down! Through the Bible God reveals His voice to us. He shows us what He is like and how He thinks through the words that He inspired others to write. And even though the Bible was written a long time ago, all of its principles still apply! God hasn’t changed! He is exactly the way He was when He told people to write the Bible.
When we read the Bible, we find God telling people what to do, and we find people either heeding or disregarding His voice. We find people who did and believed the wrong things, those who did and believed the right things, and we find God correcting the wrong and rewarding the right. We find a lot of people at their worst, and we find God punishing wrong and yet forgiving people. We find people searching for God’s voice, and we find God speaking to them at the right time and sometimes being silent. In essence, we see the character and mind of God through the written experiences of others, and we get to hear what He said to them. (See also 2 Timothy 3:16)
This is why it is important to read the Bible. Much like you’ve gotten to know a friend’s voice when you hear it in a crowd, you need to sit and spend time with God to know what His voice sounds like. Then while you are walking in your life and you hear a voice telling you what to do, you can discern whether or not it is God. God’s voice to you will never disagree with God’s (written) voice to you. Because there are many voices you will hear, but only one is always true and right.