Our country is founded on the idea of separation of Church and State, so that people can worship God or not, in any way they choose. I personally am not concerned with other religions, but as for Christianity I believe that Christianity is irreconcilable, with the very concept of politically and socially based change. I do not see Christianity as some kind of partitionable aspect of our lives or that we should look to create Christian compatible versions of everything.
The very concept of Christianity is at war against the ways of the world and despite the Biblical laws to follow government rules, we are supposed to resist thinking like the world, and embracing its way of life. The only way we can do this is by Christ's direct divine intervention in our lives. Even though our future depends on our choices its God's choice to die and rise again for us that truly liberates us.
Being Christian is not just one among many equally good religions and it is not reducible to just following a set of rules. It is about personal spiritual growth through Christ's help. It is about overcoming addictions. This is fundamentally different than following laws as while they are overlapping, they are not the same.
I fully agree that we should follow all the government's rules, but this is not enough. There are many things that are illegal that are corrosive to the spirit like worship of other Gods, divorce, sex outside marriage, excessive gambling, gluttony, drug use, vanity, gossip, hazing, being a workaholic and the like. We need to first transform our minds, if we are to transform our world, and, in turn, the whole world.
We often think of some things, that we know are bad, but think they won't affect others, as vices. The problems relate spiritually, but not just like that. The very concept of addiction leads to a point of desperation, that a person will compromise everything, for their fix. Their behavior becomes obsessive compulsive and just continues to get worse, until they can accept they have a problem and make the decision, to stop, with outside help.
So the problem with promoting the morality of the Bible in the forms of laws first is that, without treating the spiritual sources of the problems, it doesn't bring about real change. There has to be a reason why we follow rules other than we get punished for not following them. People need to be inspired, to take on the challenging reformation of their morality.
The thing that really discourages people to deal with life primarily from a spiritual point of view is that faith isn't visual. We want to see results. Even in politics, you can eventually see some changes. But the very concept of faith is that you live it and make choices to further it, without understanding how or why it works.
Praying for God's will, instead of our own, requires great courage and it is hard to believe in a God who speaks so softly and so rarely, but you will be able to see the changes in your own life and those of your family and friends. It is hard to believe in a God who allows suffering, but God only calls us to believe what He promises.
God has not created evil in any way and does not promise to stop it, but rather lets people run their own governments and cultures how they want to. But God still does intervene all the time. I am not comforted that God will protect me from all suffering, because He never promised that and He never created the problem, in the first place. It is, however, hard to fully trust a God, that uses the suffering we already have to deal with, to help make us more mature.
We can see that, even in times when the government claimed to support Christianity, our leaders till did bad things. The real difference now why evil has grown to much in the last few hundred years is that we have more power than ever before and have opportunities greater than ever before. These same things that can make life better, for the disabled or the poor, are a double edged sword and allow for greater suffering, to everyone, as well.
Many times throughout history, the Church has sided with the government and it is a big reason why many people reject Christianity and what has made our society as a whole reject religion in general. Government will always be corrupt, because the people who are drawn to it get addicted to it and will do anything to win an election and stay in power. People who like power tend to be unwilling to listen to others, with superior knowledge in some areas than they have. And finally, the only people who usually get into power are the cruelest, because only the meanest will survive against the opposition.