James 2:18-19…18 But someone may well say, “You have faith and I have works; show me your faith without the works, and I will show you my faith by my works.”
How could a person show his faith without works? Can a dead sinner perform good works serving Jesus? No! But, when you trust Jesus you are “created in Christ Jesus for good works, which God prepared beforehand so that we would walk in them.” (Ephesians 2:10). Being a Disciple involves trusting Jesus and living for Jesus; you receive eternal life, then you reveal eternal life.
19 You believe that God is one. You do well; the demons also believe and shudder.
When Jesus was ministering on earth, He often cast out demons; and He gave that power to His disciples. In Ephesians 6:10-20, Paul admonishes Disciples to claim God’s protection and defeat the spiritual forces of wickedness.
What do demons believe?  the existence of God [Job 1:6-12];  the deity of Jesus. Whenever they met Jesus when He was on earth, they bore witness to His sonship (Mark 3:11-12);  the existence of a place of punishment (Luke 8:31);  Jesus Christ as the Judge (Mark 5:1-13).
The man with dead faith was touched only in his intellect, but the demons are touched also in their emotions. But it is not a saving experience to believe and shudder. A person can be enlightened in his mind and even stirred in his heart and be lost forever. True saving faith involves something more, something that can be seen and recognized: a changed life.
Faith that is barren of works is not saving faith even though the intellect and the emotions are involved.