A lot of people who aren't religious like to think of faith as "belief without evidence" or "belief without reason," but I think faith is a lot more nuanced than that. Religious people take the original concept of faith and abuse it by claiming it's their means of knowing the Bible or the Koran or whatever is true, that's why non-religious people think of faith that way. My definition of faith is close to 🌺 AnayaOhNo's, "Having hope and belief in a positive outcome or reality through unknown means?", but with the addition that the source of this hope and belief doesn't necessarily have to be arbitrary or wishful thinking. It could come from experience--many, many lifetimes, eons of experience, perhaps--that we remember on a soul level but don't have access to the specifics of on an egoic/brainal level.