I think that there is a way of holding faith as provisional which actually supports the efficacy of that faith. This is not what I would call doubt. This way of holding or rather regarding your faith places more weight upon the object faith than on the act of being faithful. The full actuality of the object of faith remains unknown and thus any notion of it and the faith related to that notion are provisional. The efficacy of this is that there arises a nagging desire to know the object. This way faith becomes a process of aspiration. In Dhamma terms this process is the path and faith is the fuel. This kind of relationship to faith is radically different to traditional western understanding of the term. I would simply use the term "saddha" but I think we as a community will benefit from the geologically slow process of nudging our English language into a more useful vehicle for conveying Dhamma.
"Beautifully taught is the Lord's Dhamma, immediately apparent, timeless, of the nature of a personal invitation, progressive, to be attained by the wise, each for himself." Anguttara Nikaya V.332