There is some truth to that statement, whatever one thinks of the person who uttered it. As EC rightly points out, the federal government has no business whatsoever messing around with the first three items, and the fourth is simply too vague to have any real meaning - unless, of course, one wants to impose by federal fiat a whole bunch of other social viewpoints.
Conservatives were outraged when the Supreme Court found some sort of penumbra emanating from the Constitution sufficient to make abortion a federal issue, and yet now, there they are, wanting to make abortion a federal issue by using the vast, coercive, power of the federal government to dictate other peoples' decisions about abortion. Conservatives were correct the first time: there is nothing in the Constitution that gives the federal government the right or the power to stick its nose into an individual's decisions about abortion; it was unconstitutional then and it's just as unconstitutional now when social conservatives try to do it.*
With respect to prayer, I have to ask of social conservatives this: what part of "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech" do they not understand? Prayer is a personal matter that sits at the confluence of freedom of speech and freedom of religion, and thus is doubly protected from interference by the federal government. Social conservatives who wish to do anything other than keep the federal government's nose out of everyone's prayers - or choice to not pray - are being just as hypocritical as their liberal counterparts are.
With respect to marriage: where in the Constitution does it say anything, anything at all, that could conceivably give Congress the power to make laws affecting who can get married and who not, whom they can marry, and whom not, and to waive the full faith and credit clause for the states on the issue of other states' marriage laws? The answer is very short: Nowhere. Social conservatives who wish to use the vast, coercive, power of the federal government to impose their views on marriage on everyone else are being just as tyrannical as are liberals and the democrats.
Which leads us back to the original point: that social conservatives could cost the GOP seats in the Senate. Too many of the policies social conservatives push are, at bottom, exactly the same sort of despotic social engineering they rightly decry when the democrats/liberals engage in it, and, for largely historical reasons, most Americans recoil from that sort of social engineering and will reject outright a politician who appears to be seriously proposing to enact those policies. If the GOP persists in allowing social conservatives to use it as a platform to advocate for their brand of social engineering, then the GOP will find itself being rejected by a lot of Americans who otherwise have much in common with the GOP on many other issues.
* There is one place where the Constitution does give Congress some power in regard to abortion: the Commerce Clause power, pursuant to which the federal government can impose regulations on abortions that have some relationship to interstate commerce (which isn't much of a hurdle in any event). However, social conservatives should be warned to practice what they preach even here: they were outraged when the democrats attempted to justify Obamacare and the individual mandate under the Commerce Clause - as well they should have been - and it would therefore be hypocritical of social conservatives to try and impose their own version of social engineering by doing the same thing they lambasted democrats for doing. In any event, the Supreme Court would most likely slam-dunk any such attempt because, as J. Roberts made it clear in his ruling on Obamacare, the individual mandate cannot be justified under the Commerce Clause; any similar attempt by social conservatives would most likely meet a similar fate.
