In Thomas Sowell's A Conflict of Visions he delineates between two basic visions of humans in politics - constrained and unconstrained.
A constrained vision of humans views people as essentially being unable to achieve permanent moral progress for two reasons:
An unconstrained vision of humans, instead, views true moral progress as being achievable - either now or in the future.
From a Christian perspective, there are good and bad points to each of them. The constrained vision has the advantage of being very similar to the Biblical concept of original sin. Humans are simply unable to progress, no matter how good our intentions or well-reasoned the process. Ultimately, however, Christians have a hope for the future in which the world is restored to goodness. Thus, the unconstrained vision tickles our eschatological hopes.
Now, I have given up hope in trying to discern the end-times as portrayed in the Bible. But one thing appears certain - the vision of the future in scripture cannot be obtained without God. That is, whether we are able to achieve relative goodness before the return of Christ, or whether we will require the return of Christ to restore goodness in our institutions, scripture makes it clear that any sustainable progress within society will require God's help.
The constrained vision is too pessimistic and cynical. The unconstrained vision is hubristic and self-important.
Thus, the conservative view of society has two components - a governmental component and a spiritual component. The purpose of the governmental component is to provide the incentives necessary to maintain a base level of morality in a fallen world. Thus, government itself should, in general follow the constrained vision of humanity. On the other hand, the Church should not be so limited. The Church should be the one which removes constraints by the power of God. God will be the power to change lives and nations and governments. Governments cannot do this, social action cannot do this, only God is qualified in this endeavor.
This, I believe, is the message of Christian conservatism in politics. We must structure our governments in recognition of our fallen humanity. But we must not limit our vision to what can be accomplished in government, but instead look to God to see what He has for us on the horizon, and seek His help as individuals, as people, as churches, and as nations to change our hearts towards each other.