Way back when, Plato philosophied that all things were divided into 2 entirely separate realms: the spiritual and the earthly, or material. This, obviously, is Greek thought and not Judeo-Christian thought, but the Church picked up on Platonic thinking and integrated it so well that we have it with us to this day. In fact, we Christians often think more like Greeks than like Hebrews. (Biblical Hebrew-thought being that which is grounded in and emanating from the 10 Commandments.)
This conflict of philosophies in the Church led to many heresies, schisms, and all sorts of unpleasantness. It also leads to just plain old everyday Christian-living that's not quite on the mark. As C.H. Spurgeon said, "Discernment is not knowing the difference between right and wrong. It is knowing the difference between right and almost right." A subtle, but significant difference.
One ordinary out-working of Christo-Platonic thought can be seen in Medieval times in the burgeoning growth of monasteries, orders, and sects. It was assumed that a person, even a Christian person, would take either the route of the spiritual/heavenly realm, or the earthly/material realm. Thus, when a person felt the call of God upon their heart, it was immediately assumed that they must abandon ordinary life and become a priest, a nun, or a hermit of some kind. It was not thought that you could remain in an earthly occupation and be spiritually-minded. Unfortunately, this kind of thinking pervades our lives today.
Today we have compartmentalized our Christian lives so well that we have our "work life", our "family life", our "recreational life", our "church life", etc. - and never the twain shall meet. But this is fractured living, and as Christians our life is to be integrated, doing all to the glory of God. (1 Corinthians 10:31) ALL, not just "church life." Have integrity at work, love sacrificially in the family, be honest in play. "The earth is the Lord's and the fullness thereof ..." (Psalm 24:1-2) As Abraham Kuyper said, "There is not one square inch in the whole domain of creation over which God does not cry, 'Mine!'" And that includes the realm of public policy, or its more common name of politics.
"Christian political activity is to be nothing more and nothing less than the declaration, "Jesus is Lord," the most basic of all Christian declarations. For a Christian to ignore the realm of politics is to ignore the regency of Jesus Christ in that area." - George Grant, "The Changing of the Guard"
We the church have fallen to the lie of Platonic thought, and have abandoned the realm of public policy and government, thinking it to be worldly, earthly, beneath us. And what happens when the church moves out? The world moves in. It is impossible for a vacuum to exist by itself. Therefore, Church, we have the culture in which we live because we have consented to it.
God's Old Testament people, the nation of Israel, did the same thing and suffered the consequences. Pretty fatal ones, nationalistically-speaking. In Isaiah 1, the Lord tells them,
"Wash yourselves; make yourselves clean; remove the evil of your deeds from before my eyes; cease to do evil, learn to do good; seek justice, correct oppression; bring justice to the fatherless, plead the widow's cause." Come now, let us reason together, says the Lord: though your sins are like scarlet, they shall be as white as snow ... If you are willing and obedient, you shall eat the good of the land; but if you refuse and rebel, you shall be eaten by the sword; for the mouth of the Lord has spoken." (vs. 16-20)
Doing good, seeking justice, correcting oppression, bringing justice to widows and orphans ... is this not spiritual work? Is this work that the Church should avoid, thinking it earthly? Not at all, but we the Church have allowed our government to do just the opposite in the very name of these things. The eye of justice is no longer blind; churches are restricted in doing good; the poor, the widow, and the orphan are oppressed as they are held down by the Government through dependence upon the State. It takes gargantuan effort for a person to break free from Uncle Sam's Plantation known as the Welfare State. We must repent of our Platonic thinking and return to Biblical principles. We must involve ourselves in the realm of public policy, or deny the Lordship of Christ.
"... God ordains civil government, it is a sacred institution and an honorable and holy vocational field, and thus those who serve in that arena are ministers under the hand of providence." (George Grant, "Changing of the Guard")
Church and Politics DO mix - may we as God's people serve obediently and righteously as unto Him.