I have to agree with Richard here. Mick asked about religion in the original government, which can be construed as the Continental Congress or the one under the Articles of Confederation. He did not ask about the role religion played in the early days of our current government under the Constitution, which has a completely different answer.

Marriage has everything to do with religion as the act is religiously sanctioned. Civil unions, on the other hand, are more secular, and thus fall under the purview of government. With government sanctioning marriage, it is getting involved in religious activities.