If the Gospels don't contain Church doctrine, should we still study them?
Yes. Even though the Gospels do not contain Church doctrine, they were written for the believer's learning. We should still study them and make application, as with Jesus' teaching that believers are the light of the world. This illustrates their ongoing value for the believer.
Les teaches that even though there is no Church doctrine in the Gospels, that does not mean we should not study them. He says everything written before Paul wrote is for the believer's learning, and he applies the same to the Gospels. Les also insists we should make application. He points to Jesus' illustration to the twelve on the northern shores of Galilee: just as a city on a hill gives light, they were to be the light of the world. Israel was promised that role but rejected it, so by application believers today are the light of the world. Therefore the Gospels remain valuable for learning and application.