So... The Creator hid the proof of His existence in the last place a "scientist" will look....... right inside himself.
Proof in the sense of belief. Philosophically there can be no proof (see Aquinas, et al. regarding Ethics and free will). Even Mother Theresa had times of doubt. Nothing inherently wrong with that, it means you're asking questions and thinking critically. Just so you keep whacking at it and don't quit in the doubting mindset.
Mmmm, the concept of conscience is not so easy. For a cheap example dogs have a conscience of sorts. They obey the law of the pack, all those social things dogs do to get along. Instinctive to do so, that is to defer to what is necessary to remain in the pack (and alive). Why should people be devoid of all instinct? We 1) are loathe to consider it and 2) have the ability to choose to act otherwise.
One can't expect words like "believe", and "proof" to retain their exact meaning when discussing the Supernatural.
For those people who have experienced an encounter with the Supreme Being, it becomes THE GREAT FACT of their lives. It is the one thing that they KNOW, in a way that is peculiar to that event.
