Believing means we imagine something without any actual feeling, sensing or understanding.
It is a picture without any basis or foundation.
Attaining something, which is the highest form of understanding is when we do not only know something with our mind, but we feel that "in our guts" we actually live through the experience, we become part of that thing we attain, or that thing becomes part of us.
This is the level of understanding or attainment we have to get to regarding the spiritual world, and the creating force.
And we can actually do this here and now, within this lifetime.
All we have to do is open up our desires, and open our eyes.
I hope this and the links below can help, all the best.
http://www.laitman.com/2010/01/the-four-stages-of-attainment/
http://www.laitman.com/2010/01/wake-up-a-free-person/
http://www.laitman.com/2010/01/can-you-taste-the-zohar/
http://www.laitman.com/2009/12/learning-to-feel-the-spiritual-world-through-the-zohar/