Only formed faith actually justifies; unformed may be called justifying as disposition
Common Roman teaching: only formed living faith actually justifies; yet not-yet-formed faith is still a necessary prerequisite disposition and may be called justifying in that preparatory sense, though alone it remains useless and justifies no one.
On Paul justified by, from, and through faith, some Romans read living formed faith working through love; others take faith absolutely as the first disposition without which justification cannot be reached. Stapleton records both without rejecting either (De Justif. 8.16-17).
Latin
XIX. Haec est ergo communis doctrina Scholae Romanae solam quidem fidem formatam & vivam actu justificare, sed tamen fidem, etiam quum nondum formata est, esse dispositionem quandam ad justificationem, & hoc respectu quoque posse justificantem dici, nempe per modum dispositionis necessariae & praerequisitae, quanquam, nisi alia accedant, inutilis maneat, nec ullum actu justificet. Inter se vero non omnino consentiunt quomodo sint interpretanda illa Paulinarum Epistolarum loca, ubi toties affirmat & contendit Apostolus hominem justificari fide, ex fide, & per fidem. Et multi quidem existimant Paulum ibi per fidem intelligere illam quae viva atque formata est, & mentem ejus esse, nos coram Deo reddi, ac haberi justos per fidem illam quae per dilectionem operatur. Alii vero putant Paulum ibi fidem absolute sumere, & prout abstrahit a fide tum viva, tum mortua; & sensum ejus esse, fidem esse primam & maxime necessariam dispositionem ad justitiam consequendam, hominemque per fidem disponi ad justificationem, & sine fide non posse ad eam pervenire. Quam utramque sententiam refert, nec improbat Thomas Stapletonus citato libr. 8. de Justif. cap. 16. & 17.