Human Sexuality. Why is it a concern to many faith groups?

There is an amazing diversity of beliefs about human sexuality among Christians, Jews, Muslims, the followers of other faith groups, and those who are not affiliated with any organized religion.

On matters related to human sexuality, Americans tend to be polarized between social and religious conservatives and liberals.

Followers of non-Christian religions differ little from Christians on matters of sexual orientation.
Conservatives from all religions tend to agree with each other: that only opposite-gender sexual behavior is moral, and then only between a man and a woman who are married to each other.

Religious liberals are also largely in agreement among themselves, and tend to value sexual behavior as acceptable if it is consensual, relatively safe and within a committed relationship.

Those of no religious affiliation -- Agnostics, Atheists, Free Thinkers, Humanists, NOTA's (None of the Above) etc. -- tend to hold beliefs similar to those of religious liberals.

All groups disapprove of sexual behavior that is non-consensual, manipulative, or unsafe. So what's the deal???