Yes, it it. It's wired into our brains. That's one of the reason's why emoticons convey so much information: we see and recognize not only faces but even emotions in just a couple of well-placed punctuation marks.
And this is precisely why we have to be able to understand why we see what we see. Just because seeing an image of Jesus in a swirl of pizza sauce might have some meaning for you does not make it any less whimsical than seeing that horse in the clouds.As for the causality, once again I put it down to that feeling of awe. If it is something important to a person whether it be Jesus or Elvis, then they will attribute it to their higher power. While if it does not cause that awe like seeing a horse in the clouds then it is just a whimsical experience.