Or are religious people deluded to start with?
If we look at the first question, we would need to consider the effect religion has on followers.
For example, followers are required to believe in an entity that is invisible, silent and completely unproven.
Also, the fundamental principals of religions state that humans have a "soul". Again there is not one piece of evidence to support such a concept and the word soul is normally used as a metaphor.
To this extent, could we say that religion influences or even, forces followers to become deluded.
It could be that religious followers are deluded regardless of religion and find themselves attracted to the abstract, nature of believing in an unknown, contrived entity. For example, comprehensive research and authoritative studies have concluded:
"The God gene hypothesis proposes that human spirituality is influenced by heredity and that a specific gene, called vesicular monoamine transporter 2 (VMAT2), predisposes humans towards spiritual or mystic experiences."
Could the delusion in some religious followers be due to both factors, i.e., hereditary and conditional? In which case would some religious followers be more deluded than others