[Spirits] who are in the faith of charity do not reason about the truths of faith, but say that the thing is so, and also as far as possible confirm it by... sense and memory, and analysis of reason; but as soon as anything obscure comes... which they do not perceive, they defer it, and never suffer such a thing to bring them into doubt, saying that there are but very few things they can apprehend, and therefore to think that anything is not true because they do not apprehend it, would be madness.Doctrine of Faith 2, on the other hand, says,
Faith itself is an acknowledgment that a thing is so, because it is true. For he who is in real faith thinks and speaks to this effect: “This is true, and therefore I believe it.” .... Moreover, if he does not comprehend a thing to be true, he says: “I do not know whether this is true or not; and therefore I do not yet believe it. How can I believe what I do not comprehend? It may possibly be false.”Doctrine of Faith 3 helped us understand that what's necessary to believe something is not so much a complete understanding of it but a sight that it is true.
Spiritual truths... are as capable of being comprehended as natural truths; and although the comprehension of them may not be clear, still when they are heard they fall so far within the perception of the hearer that he can discern whether they are truths or not; and this is especially the case with those who are affected by truths.