"There can be no liberty while Progressives are manipulating law to remake the universe according to their delusional vision."
But... the suggestion from the original poster was that there should be -no- laws when it comes to marriage, just as there are no laws when it comes to prayer.
"Since natural law is God's law, the two are perfectly aligned. Anything the government does that violates God's law, then, it does illegitimately."
It is fair enough to say that government should work within the confines of natural law... but that doesn't mean government should act as God and claim dominion over subjects that fall outside of its limited role. So what is the role of government? The non-aggression principle would suggest that government should only exist to protect individual liberty. Consenting individuals who enter into contracts together may or may not be violating God's law, but they are most certainly not a threat to any individual's liberty. With that in mind, it is God, not government, who has jurisdiction over the issue.
A government that stays within its bounds and does not legislate the definition of marriage -at all- is not "violating" God's law. It is leaving the authority over it where it belongs.