...the law makes sense to us already; the gospel has to be told by heralds. (Ch. 1)
Human nature. We all have it by virtue of being human. So why is it that we look at the human nature of the Pharisees, and can wag a finger at them, while not realizing that those same human tendencies exist within us?
The law makes sense. Give me something tangible that I can see and hold on to. None of that blind faith stuff for me. Tell me what kind of movies to watch, how long to wear my hair, where to draw the line with my girlfriend, etc. Give me details!
Having a law just makes sense to us. But the gospel frees us from the law. We are not saved by the law, we are saved from the law. Now we become a law unto ourselves. (Paraphrase of a Matt Chandler quote.) That law is not written on tablets of stone, but on our hearts!
Enter the gospel. Not written on tablets of stone, but heralded by angels, Jesus himself, the disciples and Apostles, and hopefully you and me!
Or maybe you could just give a something to hold on to. A tract or Bible with all of the important verses highlighted. Or just a list of the top ten rules. That I can handle so much better.