Our brains are marvelous creations. They can store vast amounts of information. We are constantly taking in information and storing it every day. Some information is junk and some is good, but our brains, on their own, are unable to differentiate the difference between good data and junk data unless at the time of its storage we looked at it critically and made a conscious decision on its validity. If we don't do this it is automatically stored as fact.
Because of this it is very important, especially when young, that our minds are only exposed to what is truth. Young people, 12 years old and younger, have very little information upon which to base critical thinking and because of this they do very little of it. They simply take everything in, storing it as fact. If you have observed young people you will have observed this to be true. Since virtually everything that comes into their brains is stored as fact, it is very difficult, if not impossible, for an individual later in life to determine truth from error, right from wrong, if the information that they have been given when young is false or mixed up. As we get older everything that we see, hear, or read is compared, consciously or subconsciously, to what has been previously stored as fact and our brains store the new information accordingly. It is therefore very critical that we do our best to see, hear, and read only what we are sure of to be fact. When we are not sure of the information that we read, hear, or observe, it is very important that we look at it very critically and make sure that it is stored appropriately or we will be setting ourselves up to be easily taken into error. This is not only important when it comes to spiritual things, but it is important in everything we observe in life.
2 Timothy 2:15