I reject the notion of the world (i.e. everything that exists) coming into being. However I do permit, that nothing may have existed. That is, worlds either exist eternally (without a beginning or end in time), or don't exist at all. Since our world exists, it is eternal.
Note that this doesn't rule out the possibilty of there existing more than one world. Of course, the typical spatiotemporal notions, applicable to any one world, don't apply accross worlds. That is, notions like "x happening in this world at the same time (or before/after) as y happening in another world" or "this world being x distance away from some other world" are meaningless. This doesn't however rule out an imposition of meaningful relations on the possibility space itself.