We are encouraged to "test the spirits, whether they be of God" - can you suggest a reliable method of doing this?
Yes. In the same way that scientists can check a discovery against existing scientific documentation, to decide whether it is likely to be realistic/viable, so Christians can use documentary evidence to see whther a new idea or teaching (spirit) is realistic viable. If the scientific discovery flies too much in the face of accepted norms, one has to reconsider it, recheck it, try to recreate it, etc. The same goes with matters spiritual.