It is very difficult, sooner or later, to have exchanges with people who have decided to believe a whole collection of things based on a book written between 2 and how many thousands of years ago?

It is also difficult to understand why some religious people get so annoyed and offended because of what I might say (say) about some aspect of what they believe.

Religions seem to be a special case. What people believe does not need to founded in our general knowledge and understanding of the natural world. They have extra ways of being offended and in the UK we have special laws - Blasphamy Laws - to punish the rest of us who are outside that faith.