Why do they have to go together?

It seems to me that there is too much of an assumption that "if you believe in X, you must also believe in Y" around, where X and Y are two totally unrelated things. There are people who might be described as "economic conservatives" (I count myself among them) and people who call themselves "social conservatives" (I am certainly not among them!) and a lot of people seem to feel that if you are one, you are the other (which obviously is not true for me).

Case in point: There are two radio stations in the Washington, D. C. area which, I believe, are owned by one company and which have been advertising, "You're sure to hate one or the other" -- one, WTNT, is full of conservative talk radio, and the other is its liberal counterpart. I occasionally listen to WTNT and sometimes agree strongly with opinions expressed there, but the other day I was listening to one of the regularly featured broadcasters, Michael Savage. He was going on and on about "perverts," by which he meant homosexuals looking for their rights. I don't know what makes Mr. Savage have such a vigorous hostility to homosexuals; perhaps he's afraid of being confused with Dan Savage, a sex-advice columnist who is gay. But it just seems to me that, whatever your sexual orientation, nobody else's sexual orientation really concerns you unless they try to seduce you, and in that case, it's the unwanted attention, and not the sexual orientation, that is the problem.

Now some "social conservatives" might say it's condemned in the Bible -- and, of course, many people's reading of the Bible would agree with that, though there are obviously some very religious gay people who read that same Bible differently. But we're in a country with a pluralistic religious composition, and nobody has a right to let his religion dictate his politics to the point of banning people whose religion differs from theirs. An interpretation of "conservatism" consistent with my own economic conservatism would be to keep government out of our private business unless it damages someone, and in that case, why get involved in anyone's sex lives unless it negatively affects someone who isn't involved.

Similarly, "social conservatives" try to impose the beliefs of particular religions on areas like abortion on others who do not believe that way, and in general seem to be convinced that their own religion's views on anything trump all others. What this has to do with the essentially "laissez faire" view of economic conservatives escapes me.

Hence the title of this post: Why do they have to go together? In other words, what do they have in common that justifies the word "conservatism" being used for both?