Why push religion on to others?
Sooo, I'm hoping that there is a reasonable answer for this, But why do people continue to pressure others into following into their religion? Is it somewhere written in the majority of religious books to convert others to follow? or to "save them". I'm not asking for religious quotes about people going to hell if they don't believe, etc or whatever religion,
But why do care so much about other people, who are merely strangers to them, don't follow the same religion as they do? Looking for any evidence for the reason why to this answer. Psychology would greatly be appreciated or anything science based, quotes from said religions would be great too, if relevant.
Opinions always welcome as well.
Thanks.