To be a radical centrist is not to try to locate oneself at some mid-point of an imagined right-left spectrum. The idea of such a spectrum is itself an idol that creates a sort of conceptual trap.
To ask if Jesus (and Christianity in general) is more compatible with American Conservativism or American Progressivism is like asking in China if Christianity is more compatible with Confucianism or Taoism.
The truth is there are ad hoc similarities between Christianity and both Taoism and Confucianism. A Christian who converts from either of those might look back and say; “Now I know what that means in the light of Christ” or “Oh, I need to change my mind and behavior if I want to conform to Jesus.” In the end, Taoism and Confucianism have a lot more in common with one another as varieties of the Chinese heritage than either of them has with Christianity as such which operates under a different logic.
The same is true for the socio-political ideologies of Conservatism and Progressivism which shape the way their adherents engage the world and others in ways analogous to faith. Rooted in Classical Western Liberalism (which is why I am using "progressive" rather then the more common "liberal" to identify one of it's sub-traditions), both tend toward
* A fetishizing of the individual as autonomous
* A fetishizing of the modern nation-state as the fundamental and ultimate socio-political reality to which final allegience is given.
* An infatuation with the notion of abstractions, e.g., justice, freedom, reason etc, as universally accessible and independent of traditions.
Given these similarities, from a Christ-centered perspective, ideological Conservatism and ideological Progressivism do not so much occupy opposite poles of a spectrum as they are more like points on contiguous sections of a dart board more or less removed from the center.
To be clear, the point here is not that the heritage of Classical Western Liberalism is altogether bad, whether in its conservative or progressive manifestations. Doubtless there is good in that heritage (the break down of a fixed class system and the realizing of the equality of women come to mind) just as, from a Christian perspective, there is good in Taoism and Confucianism.
It is also true that even centered Christians will have sympathies one way or another. But, we need to be wary of investing too much emotional energy or loyalty in political parties, movements, and ideologies lest our allegiance to them compromise our allegiance to Christ and inhibit our ability to love our neighbor.
If we are not suspicious of these loyalties, we will again and again fall into the trap of trying to fit Jesus and Christianity into those loyalties. The result is a fractured and compromised Church with no witness. The religious right seeks to make God, Jesus, and Christianity safe for conservative values. The religious left (which is much more common in the Episcopal Church) seeks to make God, Jesus, and Christianity safe for progressive values. The one ends up playing servile chaplain to the red states while the other plays servile chaplain to the blue states. In their utter conformity, neither has a truly prophetic witness centered in what God has done and is doing through Jesus Christ and the Holy Spirit. Because both are content to repeat the prejudices of this world, neither is able to bear witness to the new creation.
A radical Christian centrism will engage Conservatism and Progressivism both critically - wary of being drawn off center - and sympathetically - seeking such ad hoc congruities as might be found. But it will not accept a view of the world in which they are poles on a spectrum along which Christians must place themselves.