Let me give you a really cool example that Ricky Gervais once told someone. If we take any book of fiction, or any holy book and destroyed it, that in 1000 years wouldn't come back as it was but if we took every science book and every fact and destroyed it, in 1000 years it would come back because all the same tests would be the same results. I don't need religion or faith and you don't either.
Let me give you some very important facts. There are ancient, almost 2,000-year-old copies, or fragments of copies, of the New Testament, that show that there were at about 25,000 copies of the N.T. back then. Today there are billions of copies of the N.T.
If there had been no development of a printing press, or other print-making media, there would still be 25,000+ (and probably in excess of 100,000) hand copies of the N.T., but there would be only (at best) a handful of copies of any particular, scientific writing.
Even today, the Bible is probably the book that has been published the most... 5 or 6 billion copies.
So, why? If the Bible came only to, say, 1 billion, it might be in the range of other, major writings. But the fact that it is way ahead of other writings, shows that there is something compelling about the Bible.
The idea that in 1,000 years religion wouldn't come back is something that is irrelevant. Why? You aren't going to destroy the Bible no matter how you try. So, the whole question is fictional.
As for faith, you need it because you don't know what will happen in the next minute. You have faith in whatever... call it fate, or the design of the universe, or happenstance, or God... faith that things will go on as well in the future as they have in the past. And you hope that they will. So as Saint Paul says, "These three remain, faith, hope and love. But the greatest of these is love."
Of course it's fictional. The idea is that if we forgot everything we know right now and everything was destroyed, we would simply re discover all the science again, however all the science fiction books, religious books, etc etc would not appear again, at least not exactly the same.