I have heard Muslims promote gender segregation and a prohibition on dating, being alone with namahrams, and touching before marriage, even saying hi to someone of the opposite sex or adding them on facebook or other social media, because it leads to zina....but I fail to grasp the severity of it, or even the connection between the two....I know zina is one of the worst sins you can commit, but why? what is the rationale for it being VERY bad? and ive known many religious Christians who have dated and touched before marriage and possibly even been alone before marriage (adults) who have likely never committed zina, and who seem surprised when I tell them what we believe in Islam, saying a truly pious person can control themselves.....could someone please explain?