Is Delusion a Dirty Word?

There are many signs that someone may be deluded but the most common of course is the belief in the supernatural.

Certainly, when it comes to religion there are varying degrees of "religiosity" and nowadays most people who say that they are religious are really giving their supposed belief nothing more than casual lip service.

But what about those die-hard religious nuts who believe in their faith as if their lives depended upon it. That of course, is what we mean by delusion, in the true sense.

We tend to attach stigmas and over-rate many human conditions and the condition we know as delusion has certainly taken its fair share of criticism. "Does that mean these people are insane, can we trust or work with deluded people" can spring to mind.

Many people like artists or musicians can use their delusion to good effect in creating great pieces of music or art. But then, they would usually know when to switch in or out of their state and recognize this.

But how about those people whose erroneous beliefs are so profound that they are in a constant state of delusion?

Do their subsequent thought patterns affect their day-to-day decision making and could those results have an impact on others?

For example, there is a well-documented case of a car that crashed several years ago. The driver was very religious and encountered a major problem with the control of his car. he was unable to resolve the issue and the car crashed killing him and his family. There were many other cases of the same problem where the drivers had the clearness of mind to avoid such a catastrophe.

The question is, can a full-time state of delusion be detrimental to not just the beholder but to others as well?