Reformed Protestants say that Old Testament believers were saved by faith alone, just as (they say) we are. Ecclesiastes 12:13-14 is problematic for this point of view.
To sum up the whole matter: fear God and keep his commandments, for that is the duty of everyone. For God will call all our deeds to judgement, all that is hidden, be it good or bad.
Both verses emphasize the importance of our deeds: we need to obey God. Sola fide is conspicuously absent from the terms of judgment specified in verse fourteen. We could perhaps say that to fear God (verse thirteen) is to revere Him, and that to truly do that one must have faith. Let us grant this. The very best that this concession affords the aficionado of Protestantish sola fide is that the writer of Ecclesiastes calls us to faith and obedience. In short, there is no basis in this passage for salvation by faith alone. Faith must be accompanied by obedience. Without works faith is dead, despite Luther’s misgivings about the epistle of St. James.