Can you derive church or grace doctrine from the Gospels?
No, church doctrine and grace doctrine cannot be derived from the four Gospels. During Christ's earthly ministry, He was under the law and confined His ministry to Israel under the law, with two exceptions. God was dealing with Israel under covenant promises, so the Gospels contain no grace doctrine as we understand it.
Les teaches that while believers should not downplay or neglect the four Gospels—any more than the Old Testament—church doctrine and grace doctrine are not found in them. The reason is that during Christ's three-year earthly ministry, He was under the law and confined His ministry to the nation of Israel, with only two exceptions. God was still dealing with Israel under the covenant promises and under the law, so there is nothing of grace in the Gospels as we understand grace. However, Les qualifies that grace has always been an attribute of God. When Adam sinned, God's grace moved Him to seek and reconcile Adam and Eve, rather than let them go or start over. That same grace means Adam will be in heaven because his faith restored fellowship with his Creator, and Eve as well.