In some of my other questions, I have read that State and church are kept separate in Christianity. I am curious to know, is there any concept of Christian state where Biblical laws and doctrines are enforced or facilitated? Or simply Christians are never supposed to strive for a Christian state?
Christianity does not hold a "church and state must be separate" view at all; that might be part of the US constitution, but : not universal - and to all intents and purposes it is not even correct in the US, since it is quietly acknowledged that you don't stand much chance of election if you are openly non-Christian (regardless of your actual views). Indeed, there are still several US states that have, as part of their state constitution, that you can't hold office unless you believe in God (to all intents and purposes, the Christian God). OK, that sounds like a technicality, until people actually try to enforce it.
Now, let's step away from the US, and look at Europe; there are plenty of places in Europe that have an established church. Which is to say: the church that is officially recognised and has power. In England, the Church of England held massive power, and it is only recently waning - but even so, the C of E has unelected bishops that have an automatic place in the highest assembly in the land. That does not sound like separation. This is mirrored in a number of other countries, where the church holds not just social influence, but genuine political power. Historically, this power was put to direct use, often to suppress and enforce the religious statutes of the time. Heresy and blasphemy have been beaten down with sticks and pyres.
My point: the premise of the question is incorrect. Whether Christianity "demands" a separation between church and state seems largely a point of interpretation; for many, the "render unto Caesar" view (i.e. separation) is adopted, but conversely Christians of various ilks have worked hard to try to bring about such a state.
When Pilate asked Jesus about the accusations made against him, that he was calling himself the King of the Jews (and thus implicitly threatening Roman rule), Jesus told him that "My kingdom is not of this world." (John 18:36)
Also, consider one of the rhetorical traps the Pharisees laid for him:
15 Then went the Pharisees, and took counsel how they might entangle him in his talk.
16 And they sent out unto him their disciples with the Herodians, saying, Master, we know that thou art true, and teachest the way of God in truth, neither carest thou for any man: for thou regardest not the person of men.
17 Tell us therefore, What thinkest thou? Is it lawful to give tribute unto Caesar, or not?
18 But Jesus perceived their wickedness, and said, Why tempt ye me, ye hypocrites?
19 Shew me the tribute money. And they brought unto him a penny.
20 And he saith unto them, Whose is this image and superscription?
21 They say unto him, Caesar's. Then saith he unto them, Render therefore unto Caesar the things which are Caesar's; and unto God the things that are God's.
Here again, he draws a clear separation between worldly government and God's spiritual authority.
We are told that after the Second Coming, Christ will reign personally upon the earth, but it seems that until that time, we are not to be blessed with a true "Christian State" as such.
There are in fact different concepts that emerged in christianity during the ages.
- Early christians that lived under pagan emperors were taught by Saint Paul to respect civil authorities and pray for them so they come to truth.
- When the persecutions ended and emperors accepted christianity, there was a temptation to accept millenarist view that Rome becomes the Tousand-Year Kingdom. It was however rejected by early Councils. The emperor became protector of christianity and the idea of "symphony" between Altar and Throne was strongly advocated (of course this "symphony" went through lot of crises, as iconoclast period shows)
- In the West where the secular power was weaker and the pastoral power stronger, Pope managed to create a papo-caesarist model of states.
- In the East again some rulers managed to subdue Church. Most notable here is Peter the Great, who destroyed the Patriarchate of Moscow. So the ceasaro-papist states were created.
- Today, especially in the west the idea of Christian Democracy is very strong (this is the option present in many european parliaments), which states that christians should defent christian values by participation in democracy.
All in all - christians always believed that a christian should have some responsibilities when ruling others. The models of this participations reflect the shape of countries they lived in.
The separation of church and state is a "Baptist Distinctive" but is not commonly held across the remainder of the Christian spectrum. To wit:
The state church of England is the Church of England (Anglican).
The state church of Scotland is the Church of Scotland (Presbyterian)
Most Orthodox denominations (Russian, Armenian, Ethopian) have specific integrations with the state. In the past, the Greek, Byzantine, and Syraic did as well.
Historically, the role of the Roman Catholic Church in Italy, Spain, the Holy Roman Empire, and many others was exceedingly close. The story of Barbarossa's pentinence in the snow was symptomatic and emblematic of a very long standing trend.
In short, it is not at all a "Christian" tradition by any means to separate the government from the church.