All orthodox Christians recognize that Jesus said to Pilate that "My Kingdom is not of this world." His last command to His disciples recorded in Acts 1 calls for the spread of the Gospel to "the uttermost part of the earth." Christ's personal example, and that followed by the disciples, as evidenced throughout the New Testament, was to spread the Gospel via preaching and witnessing. While there were some unfortunate exceptions to the rule, notably during the Crusades (which, FWIW, were an attempt to recapture formerly Christian lands that had been conquered by the Muslims) and by the Spaniards in Latin America, the Christian faith was spread throughout the world through the means via persuasion and not compulsion.
Agreed, but you have to realize that when you attempt to make that faith a political platform, you are talking about ultimately incorporating it into a legislative agenda and if successful, will result in compelling people to support it.
American law is founded on the basis of English common law, which drew from Biblical examples to a large extent. As an example, Blackstone's Commentaries on the Law make far more allusions to Biblical verses than to secular authors. Because of the effects of the Enlightenment on American thought and the wide religious diversity of the American colonies, the Founding Fathers largely rejected the concept of union between state and church. Because of the religious diversity and the wide support for a limited Federal government, the Constitution forbade test oaths to hold public office and denied the Federal government the power to intervene in religious matters. However, the state constitutions of the Founding era mostly recognized the existence and, in some cases, the sovereignty of God and asked for His blessings. Test oaths continued on the state level until the 20th Century.
American political rhetoric from the days of George Washington to Harry Truman made frequent allusions to God, in a context usually indicating the Judeo-Christian God, and to specific Biblical passages. Even political liberals like John Kerry or Bill Clinton, despite the secular humanist bent of their political philosophy and their nonadherence to the sexual mores of their respective churches, make it a point to be seen as faithful churchgoers.
All political thought is ultimately grounded in morality, which in turn is predicated on metaphysics. The question arises: whose political thought will be reflected in the laws of the land? If secular humanists, like the RINOs in charge of the GOP, tell Christians to leave their beliefs at the church door, it is those secular humanists who are trying to foist their morality upon Christians.