What is the latin word for by faith alone?

There's no Word in Latin (that I know of) that would express this. The best way I can think to translate this is with and ablative of means and an adverb:

fide solum

Keep in mind that I am NOT currently a Latin student specializing in the reception or even Medieval Latin (which would have more biblical stuff like this). My knowledge is largely concentrated on the late Republic and early Empire. There may be another single Word in later Latin by which one can convey this idea.