1. Most theistic laypeople have a belief in the soul that includes it somehow being within or somehow internally connected to their body.¹
2. Their belief likely also includes a conception of the soul as immaterial.²
3. Immaterial things cannot have spatial extension.
4. To reside in a place, like within the body, requires spatial extension.
5. This means that a consequence of (2) is that the soul cannot reside within or be connected to the body.
Conclusion: Most theistic laypeople have a belief in the soul that is internally contradictory [from (1) and (5)]
¹I haven’t tested this hypothesis, but I think a survey of the average person’s conception of the soul would bear this out. Certainly popular level portrayals, like movies, give this sense.
²For example, ask a person who believes in the soul to point it out on an x-ray or to a surgeon.