One of the difficulties with combining science and religion is that science typically deals with predictions that can be falsified by experiment (allowing theories to be created and tested) whereas the main spiritual tenants of religion tend to take the form of non-falsifiable hypotheses.
For example, many forms of the hypothesis that ‘there is a God’ cannot be falsified, as it is not clear what evidence would constitute a refutation.
This is in contrast to many other hypotheses associated with religion, such as creationism, that makes specific predictions that can be falsified – e.g. in one of its forms, that the world was created only a few thousand years ago.
Gilbert starts off his article with a commonly produced but mistaken assumption: “no one has yet produced a shred of empirical evidence for the existence of God”.
Here he mistakes ‘empirical’ for ‘experimental’, as empirical evidence is that which is based on experience and observation, of which experiments are only a certain type (albeit ones that are formalised and highly valued).
There is certainly plenty of empirical evidence about. Many religious people will be able to provide examples of how they have personally experienced the effect or presence of ‘supernatural’ influence in their lives, or can provide examples where many people witnessed a supposed example of divine intervention.
The question is not over whether there is evidence, but whether it is valid (the phenomena was genuinely as experienced) and how it should be interpreted (whether it supports the concept of the divine, or a particular idea of ‘God’).
Link to article “The Vagaries of Religious Experience”.