If someone says "I'm not religious" what does it mean?Can you guarantee that such a person will not insult any religion in their lifetime?

I'm not religious and I never insult any religion. I'm an Atheist.

It just means they don't follow any religion. You can't tell from that whether or not they would insult a religion. Some do, some don't. And depends what you mean by insult. Some people are insulted just by honest criticism of their religion. But I find that if a religion has particularly immoral teachings, which some do, then by criticizing them you will inevitably be insulting many people who follow that religion because they don't want to hear that their religion is abhorrent. The fact that a religion might be very harmful in its teachings while being so close to so many peoples' hearts and such a big and important part of their lives is what makes it such a difficult subject. Some people choose not to criticize religion out of respect for people. Others disagree strongly that religion should be exempt from criticism.

Edit: merchandise, Do you mean the person's carelessness in and of itself can hurt religious feelings or are you saying that people not caring about a religion can lead to religious feelings being hurt because I'd agree especially if the religion is harmful to society because that will attract criticism and opposition.

You do not have a legitimate complaint in the world.

Cheers!

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If someone said to me, you're not religious I would probably say, how do you know? Would I take it as an insult? NO.;-)

For some, just saying "I'm not religious" is an insult. Some people like to assume that all people are religious but it just isn't true. Some religious types are more comfortable around people who practice a different religion than none at all. Doesn't make sense to me but then again religion in general doesn't make sense to me (because I'm not religious).

Exactly as stated, they aren't religious or follow any religions.