I suppose they could exist. But for me taking the gods out of Vitki work leaves the practice awfully dry and barren. Without the gods all that is left is a shell. It takes away all the wonderful possibilities of the practice. Here’s why I feel this way.
Rune work without the gods leaves you with a rather bland and tasteless experience. In its simplest form it becomes rote divination. Without accepting that the runes are in fact a form of direct communication with the gods you are left with symbols that have direct meanings. By allowing them to be a link with the gods whole stories unfold. Meanings take on nuance. The multiverse is at your fingertips. Without the gods you are left with little beyond surface meaning. The gods give the casting the flesh and blood on the skeleton created by the staves pulled. Acknowledgement of the gods provides depth otherwise not accepted. For me in this regard the gods are all.
What of magical uses of the runes? Without the gods for me it just doesn’t exist. Magic requires the divine to work appropriately. Without the gods magic becomes simply an act of will. And as any magical worker will tell you will is only the barest minimum of the working. When we don’t accept the divine magical workings fall flat on their faces. Without the gods you are again left with a shell of the possibilities.
Seidr work without the gods is simply trance. Anyone trained well enough can achieve trance states. It’s in the communication with the gods and entities of the beyond that things get truly interesting. Then once again the multiverse unfolds for you. Insights and wisdom make themselves known to you. True meaning can be found. Questions can be answered. A wealth of information becomes yours. You can actually do something with the trance. It’s more possibilities open to you.
These are just a couple of quick examples of why I don’t believe a true Vitki can be an atheist. You just cut yourself off from too many meaningful experiences that way. To be a true Vitki for me requires a strong belief in that which is bigger than ourselves. Without a belief in the gods you are left with sheer arrogance.