Romans 10:17 (NKJV)
Have you ever wondered why some people do the things they do? It can be very interesting to be in places like an airport where you can see a wide variety of people with a wide variety of ways of doing things. But just looking at people and how they act will never fully reveal the motivation behind their actions and lifestyle. To really know why people do things the way they do you would have to find out more about those people and their background; what is it that has shaped the life of someone to cause them to be who they are? The answer is that people are shaped by the things they hear.
What we have heard, whether good or bad has had an influence on us and helped to shape us into the kind of people that we are today. In Romans 10:17 it tells us that faith comes by hearing, what we hear will do something in us. The things we hear have an impact on us, for good or bad, and will eventually dominate our lives. Some people would disagree but can you find a successful person who always talks about and listens to words of defeat and discouragement? Can you find a person who has a terrible life who is always talking about and hearing good, positive things?
God has given us His Word to build good things into us; faith, wisdom, and strength will all come through hearing God's Word but doubt, depression, and confusion will come through hearing something else. We should not just listen to everything and anything that is available to hear, and we certainly do not need to read everything that someone might write in a book or put somewhere on the Internet. What we hear will build something into us. There are many things we can hear but we need to put God's Word in first place above everything else that we might listen to, read, or say.