No, not necessarily (though the LP platform shows the party is trying to walk a pretty thin line). Murder and marriage are laws that the Federal government have traditionally left up to the states, and I think that is the best way to handle it in a Constitutional Republic.
We legislate against all kinds of sins -- murder, theft, assault, and so on. These laws are best left to the states, since, imo, it is within their purview according to the Constitution of the U.S.A. From the standpoint of the state, they are not legislated against because they are sins, but because they harm and/or infringe on the rights of others. Abortion certainly does that!