We know that we are saved by grace, through faith, so that no one can boast. We know also that we are saved by faith alone, sola fide. But we must take care. What kind of faith can be trusted to go out alone?
Whenever we make theological distinctions, we have to be careful not to act like a high school biology student dissecting a frog. We are to live (and do our theology) in the same integrative way that we worship the triune God—we distinguish without separating. That said, our fathers in the church, both medieval and reformed, taught that faith had three aspects—assensus (or assent), notitia (or knowledge) and fiducia (or loyal trust).
The Scriptures say that the just will live by faith. The Hebrew word that Habbakuk uses here is most commonly rendered as loyalty. The New Testament translates this with the word for faith. What does this tell us? It tells us that faith contains within it loyalty and fidelity.
And this is why James tells us that a certain kind of faith is actually demonic. You believe that there is one God? Good for you. You think that certain doctrines are true? You know that God is one? There is nothing in this that the devil himself cannot affirm. In the current controversy afflicting the Reformed world, there are some who actually say that true faith is nothing more than mere assent to propositions. This is not merely erroneous—it is the soul destroying doctrine that undergirds all forms of modernism.
Now, you are here to worship God as a central part of your expression of your covenant loyalty to God. Biblically speaking, this means you are here in faith. You hear His word, and not the word of another. You have been washed with His water, and have refused other baptisms. You have gathered to His table, and have repented of taking morsels from the table of the world.
This is fidelity. This is loyalty. This is faith.