Laws governing marriage were some of the first laws in the Colonies, dating back to the Mayflower Compact. The reason for this is that a marriage is the joining of estates, and in order to prevent fraud a system of “notice and opportunity” was set. Notice in that the intent to marry was to be published in the town and/or church of the woman with ample time so that interested parties were made aware of the upcoming event. Opportunity in that an objection could be raised during the ceremony. Traces of this remain in the traditional vows with the open question “If anyone here present knows why these two should not be joined in holy matrimony, let them speak now or forever hold their peace.”
Marriage remained within the purview of the Church for many years, without the requirement for any sort of “license”. What is a “license”? It is permission to do that which would be illegal from the entity which would otherwise enforce the illegality of an action.
What may be illegal about a marriage? Well, there are concerns about the legal status of the ones to be married. They must be of age and legally competent to enter into a marriage. With polygamy being illegal, this also means that neither party can have a living spouse at the time the marriage is entered into. Legal competence was also an issue with a slave.
What the marriage license does is place the onus on eligibility verification on the state.
I used to know a man who married in Michigan legally without a license. He did the research and the notice and opportunity statutes were still on the books. He fulfilled them, found a minister who understood that when fulfilling the notice and opportunity laws no license was needed and bingo. Legally recognized marriage without license. This also means that the state is NOT a party to the marriage. It is unknown how this may impact a divorce from such marriage.