Why do we need to come through the Scriptures?
We must come through the Scriptures because all these things have been building and building, so that through the comfort of the Scriptures we might have hope. The Scriptures are the channel by which God's progressive revelation delivers comfort and hope to believers.
Les explains that we have to come through the Scriptures because all these things have been building and building, so that through the comfort of the Scriptures we might have hope. He then moves to Galatians to show how God deals on progressive revelation, where the Law—specifically the Ten Commandments—was our schoolmaster to bring us to Christ. For 1,500 years Israel was under that Law, a system by which God was training and teaching them, hoping to bring them to maturity so they could be vessels to reach the Gentile world. Though it didn't happen as hoped, that was God's purpose. The Scriptures, therefore, are the means by which this cumulative revelation and comfort are received.
For whatsoever things were written aforetime were written for our learning, that we through patience and comfort of the scriptures might have hope.