Why are Christians interested in legislating sexuality?
Well it’s not just a Christian issue, it’s an every person, every culture, every nation kind of issue. The legislation of morality is pretty much all that states do. So it’s not a question of if sex will be regulated and legislated – it’s just a question of whose morality will guide that process.
If a sexual act is an immoral activity that has an effect upon the public and private lives of the community it should and generally will be regulated. Those are the things that are regulated by law; those with a consequence the community must bear. So theft, murder, assault, marriage, sex and who you have it with and under which conditions (fornication, adultery, homosexuality, prostitution, marriage, divorce, polygamy, pedophilia, pornography and beastiality) are regulated by the state to preserve the good of the person and the well being of the community.
They are also regulated by the church as the institution ordained by God to the spiritual well being of the person and the community.