I think that believing is seeing to an extent. Our brains perceive the world, and our brains bias what we think the world is. On the other hand, seeing something does not mean that we believe it; our eyes are often tricked.

Seeing is believing, we call it reality. This is commonly used as we see to belief. Believing is seeing, we call it faith. This is more to religion as you belief in something you have not seen but trust that it is as real as being seen.