Are Paul's & James' Messages Contradicting?
No, Paul and James were in agreement. Explaining why the confusion, on this page.
In those days, Paul pressed hard the message of "by faith alone; not by works", meaning "not by works of the flesh". This was because there were Jews around confusing the early Christians. Example, you still have to be circumcised, you still have to refrain from eating certain foods, etc.. The Jews were very integrated with the Greeks in those days.
Paul kept drilling-in the message of "No, it is by faith alone; you don't need to do anything else in the flesh..." Then the Protestants got a hold of this, and translated it as: "No, it is by faith alone; you don't need to do anything else; nothing, nothing at all."
James Stressed Other Aspects of the Message
James on the other hand, stressed "show me works, I show you faith..." Which seems contradicting to Paul. But in reality it is not.
So too, faith by itself, if it does not result in action, is dead.
What James is saying is, "faith" produces good works, and not the other way around. In other words, James did not say our salvation is based on works. Also note that James is speaking about the new-covenant after the coming of Jesus. So no need to complicate this by connecting back to Abraham, although there are some similarities.
Jesus said the same thing as James, here:
You will know them by their fruits.
Paul and James are in agreement. They stress different aspects of the same faith message, but nothing contradicting.
So What is the "Fruit"/"Action" Being Produced as a Result of Faith?
The Bible talks about a variety of them. Most notably: Spiritual maturity, increased knowledge of God, love God, love all people, compassion, humbleness, miracles in the name of Jesus.
The flip side of this, is people declaring belief in Jesus and born-again, but behaving otherwise in public. Examples, foul language, making jokes about God/Jesus, laughing along with others who make jokes about God/Jesus, attending questionable public parties even ones that seem normal in today's society but likely detestable to God.