It doesn't make a whole lot of sense to throw out evidence of God's existence and interactions and then say if God exists and interacts, then we should be able to see evidence today. There are billions of people who have seen evidence that God exists and interacts, which is why they are theists.
If I might, many of those billions do not believe based on evidence, but based on faith, custom, culture and comfort.
And it may very well make sense to throw out so-called "evidence" - old books and the like - "of God's existence and interactions" in the past, because one thinks that those are fantasies and fairy tales. There has, after all, been "medicine" practiced for millennia, but it probably wasn't until after 1900 that doctors, on average, actually extended their patients' lives. Before that, the fairy tales and quackery, truly believed and piously taught, caused men to do things that harmed their patients on average more than it helped. So it is perfectly reasonable to discard all so-called "evidence" before the 20th Century as unreliable. It is also not unreasonable to assume that a God who interacted with the world throughout past centuries, with so many saints and records of miracles, would also do the same in the 20th and 21st Centuries, and to expect to see evidence of such things in the hear and now to evaluate scientifically. Indeed, that's what the International Scientific Committee at Lourdes has sought to do for over a century, recording in modern medical detail the various healings and claims of healings at that site. Most people are not theists because of Lourdes. They believe because they were taught it. But Lourdes has made theists out of some who have delved into the miracles there.
Of course for some, no internal cures are enough. They must have the healing of an amputee, or it's not real. When they get that, it will be interesting to see what happens.
If every explanation required knowing its explanation before we could believe it, then that would resort to infinite regress and we couldn't believe anything, so it is not necessary to know the cause of the cause of the universe in order to know that it was caused.
While that's true, as far as it goes, we don't actually know that the universe is caused. After all, what was the cause of God? "God always was and always will be", it might be said, or "God is the uncaused first cause". But this is simply begging the question. God is an entity added to explain a thing, the universe. But if God can be uncaused, then also the universe itself might, too, be uncaused, obviating the need for a God to start it. It cannot be demonstrated that the universe requires a cause any more than it can be demonstrated that God does.
Likewise, if we discovered a large artifact on the dark side of the moon, then it could be reasonable to think that it was created by aliens even if we knew nothing else about these aliens. So do you think it is more reasonable to think that the universe has a cause even if you don't know what the cause is than to think that it does not have a cause?
The artifact would have to be artistic, something that nature could not do. For example, if I drove through the snowy woods and I passed a scale-model replica in snow of the Statue of Liberty, I would know for certain, without a shadow of doubt, that human beings had made that, because all of my experience with Nature shows me that a chaotic thing like snowfall cannot spontaneously form a statue. So if I see a statue, then I know that a creature made it. And if I sat watching the snow, and I watched the snowflakes spontaneously form the Statue of Liberty with nobody there to do it, I would know that invisible beings of some sort were doing that intelligently, because it is flat out impossible for entropic systems to spontaneously become highly ordered, with a massive increase of information content, through random chaotic action. The world does not work that way and we all know it. So yes, if there were a statue on the far side of the moon, that would mean that there were alien beings of some sort, or perhaps that the world existed long ago and had civilization, which was then destroyed, and we're only just getting back to that.
"Faith" is synonymous with "trust" and it doesn't make much sense to trust God to exist, so we must first have reason to believe that God exists before we can have faith in Him to do something.
That is logical.
Understanding a scientific and psychological phenomenon does not show us whether or not a deity is causing it because that at most simply tells us how the deity is causing it.
It depends on what it is. The Statue of Liberty spontaneously forming in a blizzard in the middle of Antarctica, where there is no human agency present seems supernatural, except for the informational content: a New York statue. As we saw that forming, we would assume that the US government was conducting some sort of secret test, not that nature was performing art.
But if the statue that emerged was the image of an angel, strange and with captured light, we would know that we were in the presence of the supernatural, of a non-human intelligence with command over nature.
The information conveyed in the phenomenon is determinative of what we will believe about its origins. If it's a burning bush that tells is that it is our God speaking, and the bush is not consumed, we are likely to recognize what this is, and to think that we are being blessed like Moses was, even if we didn't believe that the story we read of that having happened was true before we saw it happened ourselves. In fact, one of the unfortunate reasons that people do fall into the possession of bad spirits is because when people have a true supernatural experience, and encounter with spirits that seem fair, they are very much inclined to think that they are specially blessed on account of that, and to thus be more easily manipulated by a thing that is not fair at all but foul. People's first instinct on seeing something wonderful and supernatural is not "I am damned!" but rather "I am blessed!"
It is perfectly reasonable to withhold belief until you find what you consider to be sufficient evidence for it, and in fact there is not a single person who has ever formed a belief when they thought that there was insufficient evidence for it.
Well, gosh, that last sentence is pretty categorical, and I don't think it's really the way people work. Most of the the things we believe we learn very young, before our rational faculties are more than barest impulses. We are told something and we believe it. We become more critically minded later in life about many things, but most people in the world cling quite tenaciously to the culture of their youth, including its religion, because they were born into it and grew up in it, and always accepted it as just so.