Once we do, and with experience, we will develop faith and doubt will be dispelled. It is like on your first visit to Wat Sanghathan. To listen to the description of the temple is not the same as seeing it for oneself. This is what it really looks like. We had painted many different pictures, but they were not like the real thing at all.
Imagination is one thing, but reality is another.
The Buddha knew reality and did not imagine things. He understood heaven and hell, Nibbana, merit and evil. This understanding can be realized within ones own mind. We still have doubts about hell, heaven, Nibbana and our own minds. These doubts slow us down and prevent us from understanding and achieving clarification.