The Veil is alive, and it isn’t alive. Compressed down into dogs and deer and things that are neither and both (in mind numbing counter-existence), it lives. But loose in the hazy blanket that filters death from live, it simply is.
The inherent problem with a semi-permeable barrier between life and death is that it implies that The Powers That Be must have intended for it to be a two-way street. Otherwise they would have simply set it up as a one-way trip with no possibility of parole.
But this implication then casts an odd light on the divine mandate of the Dogs. Why punish someone for doing what they specifically allowed to be possible?
If, like Jon theorizes whilst talking to Phil, that the flexible nature of the Veil is simply part of the ‘free will’ aspect of reality, then the Dogs represent a rather tangible manifestation of the punishment for sin. Much like the ‘don’t eat the apple’->’dammit, I said don’t eat the apples! *banhammer*’ storyline.
However, as Phil maintains, it could also simply invalidate the mandate. If The Powers That Be willed it closed, it would be closed; therefore that wasn’t their intention. Their whole argument rests on the fact that the Dogs misinterpreted their mission.