'Faith-in' is the disposition to believe in something, or as having a particular, committed worldview. It is thus personal, an individual's commitment. It does not depend on doctrinal formulas and propositions. 'Belief-that' on the other hand "indicates a disposition to believe that a proposition is true; it is impersonal in the sense that it is independent of the person making it" (p. 141).
Momen analyses these concepts further, and I will compile the following quotes from his book. The quotes are not direct, because I want to edit them a bit.
Faith-in involves an element of trusting in the object of one's faith; it involves the feeling that the object of one's faith is in some way greater than oneself and is able to lead one to greater fulfilment and happiness; that one can trust it to act in a beneficent way.
The factor of trust leads naturally to the feeling of dependence one the object of faith; a feeling that one can, with confidence, rely on the object of one's faith.
Part of the faith-in relationship involves a sense of loyalty and faithfulness towards one's object of faith, together with confidence that this is reciprocated.
Faith-in involves a great sense of love towards the object one's faith and a feeling of being in turn loved.
One aspect of faith-in is the willingness to obey the instructions of the object of one's faith.
One aspect of faith is the feeling that one would be willing to sacrifice for the object of one's faith. There is also often the idea that the sacrifice is mutual, that the object of one's faith has already sacrificed for one.
Faith-in is accompanied by a feeling of certainty concerning the promises made in the scriptures, together with the disappearance of the feeling of doubt and meaninglessness.
The consequence of faith-in should be seen in the life of the individual. Faith-in leads to a focus and direction for one's life. It ats as an absolute standard for one's conduct.
(Pp. 142 - 143.)
In belief-that, dependence is expressed in such doctrinal formulas as determinism (that all of one's circumstances and actions are already predetermined by God).
Most religions have a doctrinal formula that emphasizes the need for faithfulness and loyalty. This is often translated into doctrines of faithfulness and loyalty to the institutions of the religion and to the religious community. Laws relating to marriage and the bringing up of children often emphasize the need for this loyalty to the religion.
Love is often emphasized in credal formulas that refer to the mutual love between God and humanity.
Obedience is expressed in the religious requirement to carry out the details of ritual law or spiritual discipline. Any deviation from the laws and rules of the religion need repentance and expiation. This aspect of a belief is also usually extended to obedience to the institutions of the religion.
Sacrifice may be expressed at the simplest level in sacrifices of one's property and wealth to the object of one's faith; it may also be expressed as a state of detachment from material things. From the other perspective, the object of one's faith is considered to have sacrificed also.
The various creeds, doctrines and dogmas express the certainties of the religion.
The consequences of faith are expressed doctrinally as being born again, englightenment, transformation, the work of the Holy Spirit.
(Pp. 142 - 143.)
Momen then goes on to explain:
Thus we can see that religious experience produces a certain disposition in the individual -- faith-in. If the believer tries to express this faith-in, he or she can only do so in terms of concepts that are available to him or her -- this immediately then enters the real of belief-that. We may say that faith-in is analysed by theologians and [philosophers of religion] and piut into doctrinal formulas that seek to express it -- and so becomes belief-that. (P. 143.)
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Momen also mentions in this context the issue of superstition (which is of special interest to me personally):
Magic and religion are not easily separable entities. Most religions have incorporated at least some magical elements, if not into the orthodox religion, then at least into the popular religion. Indeed, if we consider the miracles said to have been performed by the founder of the religion as magic, then almost all religions have what may be called magic even in their orthodox elements. (P. 144.)
I have nothing to add to that statement for the moment, except my endorsement. This is an issue I will no doubt visit again, as will Momen in his book.