No its not harmful, nobody gets hurt. Telling people they have to agree, or think a certain, now that is harmful, whether coming from a religious mouth or yours. As long as people do not harm others, hinder others, restrict the rights of others, ostracise others, bully others, fire/exclude others based on religious beliefs/non-belief we are good. Like take for a example the abortion debate happening right now in Ireland, (I'm Irish). There is a live discussion about whether to remove it from the constitution, and I am totally in favour of it as it is an example of religious belief impacting on public policy. But if you asked me if I also think that my own mother is deluded because she goes to mass, I would have to say no. THat is this weird, feigned 'matter of fact' mentality that floats around websites like reddit as an attempt to make its users feel really really smart, and certainly smarter than certain groups of other people. If you, or anybody else actually thinks that belief in religion is tied with someones intelligence or mental state of mind you are a moron. And by belief, I refer to normal everyday belief. The person who goes to mass once a week, the normal person. Not the Westboro Baptists, not IS or Al Qaida...the normal people.

To reiterate, anybody who uses their beliefs to harm others are dangerous, but if your belief is private, and makes your life easier, happier or fulfilled while not impacting on others there is nothing wrong with it. Now you may be American, the land of the free and the fucking ridiculous, so maybe you are only thinking of the people who picket funerals, or the ones who are creationist or who want evolution removed from schools, or the ones who don't send kids to school at all, or the ones blowing themselves up and killing hundreds of others with them, and in that respect do I think they are harmful, of course. But you know, and I know that they are vast vast vast minority.

What, may I ask, is your problem with somebody, even if you must call it delusional, but what is wrong with somebody who publicly is perfectly functional, but privately is deluding themselves, but this delusion makes them happier and more content, or helps them deal with the death of a family member or whatever; but what is wrong with that person having private faith if it helps them personally to cope with the day-to-day?