I mean complete bible law in Christian countries.
One of the problems is that because Christians do have different interpretations of scripture; a leader, group, or denomination would have to ultimately set laws against the convictions of other Christians. For instance, some Christians, although I think a small minority, believe the bible speaks against celebrating Christmas because of pagan roots and an identical description of a Christmas tree in the book of Jeremiah. So many like myself would be forced not to celebrate a holiday I believe honors Christ if a leader held that conviction and deemed Christmas illegal. I feel it best for Christians to celebrate, or not celebrate according to their conviction.
If they were non religious, this would make sense. If they believed in God, it wouldn't.
The theocracies in Europe were controlled by denominations. So this lead to many problems including laws against possessing a bible, and executions. Theocracies were more church controlled than scripture controlled.
How is this bad?
As an example, if America became a Baptist nation, Pentecostals may be prohibited from some of their practices like speaking in tongues.
The founding fathers understood this would be a problem, so when they held Sunday services in the Capitol, they used different ministers from different denominations. And Massachusetts had an earlier problem when they employed a Puritan theocracy, which lead to the persecution of the Quakers.
A majority of America is christian though, so wouldn't they just implement Christian law and any non Christian could leave the US?
What exactly do you mean? Are you referring to the Old Testament laws, or the Bible as a whole? I ask that because some feel that the NT is unrelated to the OT.
I personally think that we either should support theocracy or become non religious. Both groups are honest and I respect the theocratic as well as the non religious. Claiming to be christian while you don't base your life around the bible is two faced and false Christianity I think.
The law of God (and thus the Bible) revolves around love. And being guided by the Holy Spirit. And belief in God cannot be forced on non-believers.