When does someone "place his faith" in a religion? If you ask a typical believer why he chose to place his faith in the metaphysical belief system to which he subscribes, he will explain how certain evidence, whether in the form of experience or history, convinced him of that system's veracity. However, this traditional conception of the faith process simply assumes that, prior to the believer's picking one religion over the others and identifying it as the sole true religion, he regarded all of the religions or at least a certain number of them as possibly true because, for him to think of his religion as the true religion, it must have been possible for it to be true in the first place. Otherwise stated, there simply cannot be any evidence for the impossible (the not possibly true). Believers must first place their faith in the possibility that specific metaphysical claims possess the capacity to be true before determining if they indeed are the truth - they must assume this possibility. But why would such a thing be assumed? Most people never think to ask this question despite the fact that faith in the possibility of metaphysical truth necessarily predicates any and all religious faith.
Some claims are possibly true while others are not. For instance, the claim "Marshall is wearing his Northface jacket" is possibly true whereas the claim "Marshall has magical powers " is not possibly true. Falsifiability, the capacity for something to be revealed as true or false through physical observation and scientific processes, distinguishes the possible from the impossible. Possibly true claims entail material things for only material things can be demonstrated and only claims that entail material things can be proven false. A jacket is a physical object and whether I am wearing it or not can be determined with observation whereas magic is a metaphysical substance and its existence is unprovable and, consequently, unfalsifiable. Unfalsifiable claims are all equally possible and impossible for they cannot be proven to be more or less possible than each other if they cannot possibly be proven at all. The necessity of falsifiability for possibility stems from the pointlessness of unfalsifiable claims. Because the existence of my magical powers cannot be proven one way or another, claims about their existence or nonexistence are of no concern.
However, one could always posit the possibility of any unfalsifiable claim through faith, which is, by definition, the conscious or unconscious rejection of logic. After positing an unfalsifiable claim, one could then search for "evidence" to support it despite the valuelessness of evidence for unfalsifiable claims and the senselessness of the search for it. It is crucial here to note that someone must first posit the possibility of an unfalsifiable claim in order to find "evidence" for that claim, not the other way around. In order for Alyona to find "evidence" that I possess magical powers, she must first posit that I could possess them for, if I couldn't, no such "evidence" would exist. Evidence is in quotes here because "evidence" for unfalsifiable claims is not actually evidence if the term is defined as "the available body of facts or information that help demonstrate whether a claim is true or false." If a claim cannot be demonstrated as true or false in the first place, evidence for that claim cannot exist by definition. This "evidence" is an illusion and the the accumulation of "evidence" for an unfalsifiable claim is an even greater illusion. There is never more or less "evidence" for an unfalsifiable claim because there is no way to know whether any piece of "evidence" actually supports the claim and because, as aforementioned, evidence for unfalsifiable claims cannot exist in the first place. For example, if Alyona learned that I carry a wand on my person at all times, she may regard this as "evidence" towards the unfalsifiable claim that I possess magical powers. And, if she later discovered a book of spells in my room, she may think that the likelihood I have magical powers has been raised even higher as she now has not one, but two pieces of "evidence." The problem is that neither one of these observations actually supports the claim that I possess magical powers because the claim is impossible. The feeling that my owning a wand somehow makes the claim less impossible is an illusion, the feeling that my owning a book of spells somehow makes the claim less impossible is an illusion, and the feeling that these two things together somehow make the claim much less impossible is an even greater illusion. Nothing can make an impossible claim less impossible; that's what it means for something to be impossible.
The religious person places his faith in existence of the possibility that the religion for which he has found subjectively sufficient "evidence" could be true. Religious beliefs, like magic, are metaphysical and thus unfalsifiable. Because they are unfalsifiable and therefore unprovable, no religious belief can be any more or less possible or impossible than another. If someone believes in X Religion, is it not because the "evidence" has convinced him for he can only begin to find "evidence" for X Religion after he has first, through faith, posited the possibility that X Religion could be the one true religion. If X Religion cannot possibly be true, if it is impossible, then there cannot exist any real evidence to make it any less impossible.
So, when does someone "place his faith" in a religion? He originally places his faith in it when he faithfully posits its possibility, not after he's gathered any amount "evidence" for the "evidence" is merely an illusion.