This a talk that philosopher Peter Kreeft gave at Villanova University in May of 2012 on Faith, Doubt, and Reason.
He gives two interesting definitions of faith: (1) Faith in an idea or proposition and (2) Faith in a person. In the beginning of the lecture, he gives a good introduction to the epistemic situation associated with those two understandings of faith.
His two definitions of doubt is also paralleled as: (1) doubt in an idea or proposition and (2) doubt in a person. Kreeft gives a good understanding of these matters in disciplines such as science, theology, and philosophy, and puts them in interesting contexts of philosophers who had predominant thoughts on all subjects (Descartes, Pascal, Plato, Hume, etc.).
Check it out!