CANON XII. If any one saith, that justifying faith is nothing else but confidence in the divine mercy which remits sins for Christ's sake; or, that this confidence alone is that whereby we are justified; let him be anathema.
CANON XIII. If any one saith, that it is necessary for every one, for the obtaining the remission of sins, that he believe for certain, and without any wavering arising from his own infirmity and disposition, that his sins are forgiven him; let him be anathema.
CANON XIV. If any one saith, that man is truly absolved from his sins and justified, because that he assuredly believed himself absolved and justified; or, that no one is truly justified but he who believes himself justified; and that, by this faith alone, absolution and justification are effected; let him be anathema.
Protestantism’s “sola fide” is an error; there is a sense in which it can rightly be said that we are justified by faith, as the Council says, but the error rejected by these canons is not it. Justification is not subjective and consequently contingent upon some internal subjective state of mind; faith is not confidence—although of course we ought to have complete confidence in God.