Trump believes same sex marriage is good. Trump us a christian. Many believe because same sex marriage is a constitutional right that it's therefore moral. It is not. Here is a link to start this conversation:
10 Reasons Why Homosexual “Marriage” is Harmful and Must be Opposed
Sorry OP should say "same sex marriage" sorry. Working on my phone with sausage fingers.
You brought up an interesting post. Here's what comes to mind when I read what you've written, for what it's worth. To begin with, I haven't noticed Trump loudly supporting gay marriage, but some posts have already pointed out that what works for the law of the land and the constitution are laws that work for all people equally. None of those laws force us to go against our own convictions, and of that I am very appreciative.
The difficulty is establishing a man-made theocracy on earth is that the law is always subject to interpretation and application, not because the Law of God or even that the Holy Spirit is limited but because our human ability to love God and love our fellow man is limited. I love the law (and Law) of God and study it regularly. It forms the basis for what Jesus was fleshing out for us - and of course, because He gave them (us) that law. The problem with the law has always been sin. On the one hand, much of the Scripture, especially the law, was given for the multitude of transgressions we humans have figured out how to commit. We needed a definition. Not to beat the old horse one more time, but in case any of us were wondering, it's just not right, it's downright wrong to steal from your neighbor or sleep with his wife. There weren't any "his husbands" or "her wives" back then, but in America, one would extrapolate that the same rule applies. But...that's an interpretation, an application. See what I mean?
Where would any set of men (or people) draw the line on the interpretation and application of God's law? Would they ban all American holidays? They are indeed all idolatrous at their roots. How about buying and selling on the Sabbath? That's banned too in the reading of the Scripture unless you subscribe to the replacement doctrines many/most Christians do, which says that somehow that age-old commandment that Jesus Himself kept sinlessly was exchanged for what the Christians now do on Sunday...except none of them do it. The Jews practicing what became Judaism had the same problem with the following concepts evidenced in the Scriptures: if we can define the Law, we can keep it. Let's all fast more often than God said, so we can be more religious and righteous than the once a year He commanded us. Let's not only keep the Sabbath by taking the day off and helping everyone else for whom we are responsible also have the day off, and let's do only what is needful or helpful for our fellow man, but let's make rules that Sabbath starts at a particular point in time and that you can't walk further than a specified distance or carry more than a specified weight. Granted, they lost a lot by not regarding the Sabbath, and all it takes is a read through the OT and you see that story, but the plethora of enforced traditions superseded the law God gave and by following their traditions they missed the point entirely - which is what Jesus showed them when He taught them. Maybe all those obscure commandments (not mixing fabrics, not planting mixed fields) have other applications than what was originally given, but who would decide? In the present system, we get to decide. We get to decide if healing a man on the Sabbath is in agreement with the law as it was given, and that's how Jesus called that shot. Carrying his mat wasn't a violation of any particular written law, but the Pharisees missed seeing the miracle right under their nose when they tripped up over Jesus flagrantly disregarding their interpretation/application of the law as held by their traditions.
In all seriousness, wouldn't we have the same problem now? I'm with you on the definition of marriage and on the general idea of the importance of hearing what God is saying and doing it. God isn't fooled and He has the final say. I'm even with you on the idea that the Holy Spirit will teach us the truth of how we should walk with God because I believe the Holy Spirit (if it's really the Holy Spirit) will remind you of what God said and what Jesus taught - which are one and the same thing. But in all honesty, if you ask a lot of believers today, they'll tell you all kinds of things that they say they are hearing from the Holy Spirit, which things I'd personally be hesitant to accept.
So if you got, say, 100 godly men in the same room to agree on what it looks like for people to be living in a theocracy, I'm not sure you could come up with better than what we already have in our constitution. In light of what could have bee decided, those founding fathers who acknowledged teh Creator of man and the rights that He gave did a rather amazing job of establishing a system that works pretty well. Seriously my concern on the other hand is with the same 100 people, you could end up with something that looks like the domination of power hungry leadership over the masses much like we saw in Hitler's regime or in the oppressed aspects of some Muslim communities. People in those situations did not fare well, whether with beheadings or other forms of destructions. That love of power is rampant. What did Peter warn them about - grievous wolves ready to wreck havoc on the church? They've been doing it from early on, probably thinking they had the right interpretation of the legalism that they defined. Again, we've been offered a perfect law of liberty - that same system God put into place that if we love Him first and foremost and love our neighbor as ourselves we could use the other definitions of transgressions and restitutions to have the best possible earthly life.
One more point here: God gave man ultimate freedom from the beginning. I can't see in any place where Jesus or the disciples/apostles took that freedom away from humans. The Judaizers tried, but for the most part the Christians saw through it thanks to Paul's interesting arguments such as he spelled out to the Galatians. God allows us our choices and our consequences. As for me, I prefer to be self-governed (self-controlled) by my understanding and application of the laws of God, whether by study (as in study to show yourself approved unto God) or by His genuine Holy Spirit (since where the Spirit of the Lord is, there is liberty) within the framework of our present constitution which allows me the freedom to worship God acceptably, knowing that I will account to Him for the deeds done in the body. I look to Him for His grace and mercy with my inevitable sins now washed by the precious blood of Jesus Christ, but I hide His word in my heart to avoid sinning not to consider His death a common or casual thing. The kingdom of God starts here and now with our individual obedient submission to our Lord and King. I'm especially appreciative that I don't have to fight a government that requires that I live by their definitions of righteousness instead of having the adventure of obeying for myself and answering to God.
I realize your post started with same-sex marriage, but if I address that part, then don't I also have to address things like Swaggart's sin, Baker's sin, and countless other sins that people who have read the Book and should have known better, have committed? David should have known better too having all those wives to begin with and then stealing his faithful warrior's wife and arranging his murder. What else is there but to repent when we realize our absolute awful error? Gays aren't alone in this sin-thing. I think if we were honest, we would conclude, as the Scriptures do, that we are all in sin - I'm in that group - and I wonder if most of the people in the same-sex category have even heard the good news that God showed us His love in His mercy, because while we were yet sinners, Jesus Christ died for us. At this point, we have the freedom to share the good news.