Living a Christian life means avoiding all sin, but this in itself is idealism, as it is impossible for sinful humankind. If Christian living includes idealism, why shouldn't Christian political views include idealism? You are in effect saying the Bible is errant and so is God, so why try to live for God by the exclusive faith in Christ and what He did at Calvary? You are literally defeating the point of salvation if you think that way.
I think there are only two legitimate political views that can be derived from the Bible: support for a monolithic superstate or opposition to government altogether. If you view the Bible as pro-state and advocating enforcing God's law through government, then you hold the view that government should be massive and intrusive in both personal and economic spheres. Any Christian who supports government involvement in one sphere but not the other (i.e. left-wing vs right-wing) is inconsistently enforcing God's law through government. If you don't view the Bible as prostate, then you are some form of voluntaryist. How do you explain God founding the nation of Israel, and allowing and controlling the whole earth, and all its nations?
Your statement is misleading, as the law is dead to those under the "Spirit of life through Christ Jesus, who walk not after the flesh, but after the Spirit", as Romans 8 says. We are under grace by faith, as Ephesians 2 explains. Your argument is flawed as it only considers one aspect, and is based from assumptions. This is not meant as a harsh rebuke, but a simple critique.
I strongly agree with this, as someone who is not a member of a political party.