So the two can go together I think, as long as the freedom not to worship is guaranteed, and I think it always has been in the U.S. and always will be. I know of no one who wants to have one iota of coercion in religious matters as public policy. From the social science data we can incontrovertibly say that the greatest strength and least amount of problems comes from the intact weekly worshipping family. The further one moves away from that the more weaknesses and the less strengths we have. There is a deep vested societal and therefore governmental interest in a high level of the practice of religion, for religion is the natural nurturer of those virtues on which a democracy is particularly dependent, as well as those virtues all societies need to flourish, be they democracies or not.
Government is about using power and law for the public good.
Marriage is at the core of the stability of society and the strength of the next emerging generation, the future United States. Government has wrecked so much of marriage law in the last few decades so that at present it offers people no benefits in law and nothing but penalties. A spouse may walk out on spouse and children and be assured that in court the government is not going to penalize and will essentially reward that action. Children and unmarried adults who look on get the message. So I would go, as an interim stage, allowing people to opt into different types of marriage contract, freely chosen.