I can't cite references at the moment, being about to go to bed and not ready to do that sort of research but off the top of my head....
"Faith", "faithful", and the descended from Latin synonym "fidelity" all implied something more than mere belief, at least before the Reformation. Faith indicates perseverance, it is St Paul's running the good race and fighting the good fight. Faith is less about belief than commitment- St Peter did not sink below the waves because he stopped believing, he sank because he lost the commitment to Christ to keep walking on water.
If we keep faith we are justified, if we lose it we are condemned. The commitment is shown as works, as St James tells us.