And secondly, a guide to expression, formation and discarding of opinions.
1. When expressing your opinion, do so in the most polite manner, rather than the most agressive one. Examples include:
"I believe the way to salvation is by believing in our Holy Lord the Flying Spaghetti Monster",
"If you've ever done something wrong (which you have!) then you're going to spend a really really long time being drowned alive in a scorpion-filled vat of rotting animals while having a painful discharge from an embarrasing orifice".
2. If your opinion cannot be disproven, it doesn't necessarily mean it's absoulte truth. Examples include:
"I believe that a benevolent green lobster floats magically and stealthily above the heads of every third person but that these lobsters cannot be detected using any form of technology."
3. Always respect the opinions of others and consider whether they may actually be correct. This may save a future potential Galileo a lot of grief.
4. If you really cannot change someone's mind about something, and suspect there are other things to do like save your neighbour's cat from being eaten alive by a very confused and possibly psycopathic child, then it would be wiser to walk away from a disagreement and do something useful.
5. Don't stop someone from doing anything unless it's something that they'll regret, or makes life difficult for other people who are just trying to make ends meet. If someone of sound mind really wants to walk into the back of their cupboard to see if Narnia exists, then really that is up to them.