If you are acting like you are married - committed and faithful to one person for as long as you both live, will God care if you have that piece of paper or not?
Marriage is a covenant that transcends a piece of paper. People who live on a desert island that lacks any organized government can enter into the marriage covenant and thus be married as God defines the term.
In a different thread, because too many politicians, judges and bureaucrats are now hostile to marriage as God defines it, they seek to redefine marriage according to their opinion of fairness. Others are happy to take advantage of this moral breakdown and to use government to damage marriage as God defines it.
It is for that reason that I now advocate the power to regulate marriage (as government defines it) be stripped from government and returned to being a private matter.
Having said that, it is good for people to have entered God’s marriage covenant to also be married as a secular legal matter, at least for as long as the state claims that power.
If a couple decide to enter into God’s marriage covenant but decline to also execute a secular legal marriage, it it extremely easy for one party to break that covenant. Thus, it becomes a double test of righteous character for a person to honor his commitments until they are terminated by the death of one of the parties.