What does the curtain represent in the Bible?

Nothing in our world—nothing even from the darkest planes in the next could be strong enough to separate us either from the love and protection of God or from the constant companionship of those who love us in the spirit worlds—nothing can do that. 

But the shadows have it in their power to draw the curtain of evil in between. 

We have to be willing and to find sufficient effort to drag that curtain aside—and all the time, the shadows tell you it is darkness itself and no veil at all.

—Zodiac, the Christ Messenger