Why is faith without works dead?
James 2 helps us to appreciate that one can believe, but to just believe does not demonstrate that one is fully convinced - sure 100%. It must be demonstrated.
There are many examples I can think of.
One is where someone says, like the apostles did, " Lord. I am ready to die with you." Really?
When it came down to it, they all scattered. They lacked faith.
Paul was willing to fight wild beasts.
Daniel continued routinely praying despite the severe consequences given. He demonstrated faith in God.
His three companions faced the fiery furnace, trusting in God.
Hebrews 12 is full of examples.
A father tells his son, "Jump. I got you."
Does the child really have full assurance? If he jumps, he demonstrates he does.
The demons believe God is, but they do not demonstrate by works that they have faith - full trust in God.
Faith is backed by works. Without works, one just believes, but that belief is fickle. It will crumble in a moments notice, and be blown by a breeze.