How can faith and political/social change combine?

I have recently been heavily influenced in my thinking by an excellent book by Jim Wallis, entitled; Seven Ways to Change the World - Reviving Faith and Politics'. It addresses the key issues surrounding how to connect faith and politics. There are many elements in the book I have found helpful and may refer to in the future, but wanted to mention a couple specifically today, which helpfully summarise how I hope to address the issue of abortion and topics related to the sanctity of life, from my perspective as an evangelical Christian.

Firstly, that in order for effective social change to take place, whatever the issue being addressed, it cannot be done so purely on religious grounds;

"I suggest that political appeals, even if rooted in religious convictions, be argued on moral grounds rather than as sectarian religious demands - so that the people (citizens), whether religious or not may have the capacity to respond" - p21

A simple 'Thus sayeth the Lord..." doesn't carry any weight with society, therefore though opinions on sanctity of life and how it should be protected, must and will continue to be rooted in scripture and the heart of God, a public discussion of the matter needs also to contain an appeal on the 'moral grounds' in order to carry significant support in society.

Secondly, this is balanced by the following, praise of the role religious conviction has previously played in social change.

"Imagine Lincoln's Second Inaugural  Address without reference to 'the judgements of the Lord', or King's 'I Have a Dream' speech without reference to all of God's children. Their summoning of a higher truth helped inspire what had seemed impossible and move the nation to to embrace a common destiny." - p36

In short, it is impossible to address political issues while leaving evangelical convictions at home, but I am also convinced that to achieve social reform, in this case the changing of abortion laws, society at large must also be united in a cause through inclusive moral language.
This, will hopefully be the approach you find in this blog.