Loki's wager is the unreasonable insistence a concept cannot be discussed because it cannot be clearly defined. It is a logical fallacy and technically an extreme use of equivocation. It can be avoided by using reasonable, clear and shared definitions of concepts.
The name originates from the myth that Loki made a wager with some dwarves, and bet his head. Loki lost the wager, and when the dwarves came to retrieve his head, Loki asserted that they could take it, but they were not entitled to any part of his neck. There are some parts which both parties agree are head, and both parties agree are neck, but neither could agree where exactly one ended and the other began. As a result, Loki kept his head.
Religion and God are words that are often re-defined based on metaphysical terms, that may only discussed on the believer's terms, to avoid criticism.
An example would be to insist religion cannot be criticised because:
- as a group, it is not responsible because made up of a diversity of believers, and
- religion in individuals is not responsible because they do not represent the entire religious group.