b) Human beings are relational beings
Whatever else it means to be in the image of God, it certainly includes the idea of being relational. Consider Genesis 1:27:
So God created man in his own image,I take it that the implication is that the plurality of man - the sameness-but-difference expressed in the maleness and femaleness of human beings - is an essential part of their image-bearing. In fact, I would say that the image of God is less something human beings have and possess and more something that they do, as they relate to one another. In this way they bear the image of the relational God who created them.
in the image of God he created him;
male and female he created them.
The implications for political systems are interesting. I think this counts against systems that tend to high levels of bureaucracy and centralised government. Why? Because it is inevitable that a centralised government and bureaucracy will tend to deal with statistics and not people; it will therefore pursue policies and not relationships.
c) There is a right way for human beings to live
If human beings were just a chance product of random evolution, it seems to me there would be no grounds for claiming that there are better and worse ways to live. At a fundamental level, ethics would be undercut, and that would affect government. In the "randomly evolved society" there would never be any reason for government not to go along with the majority (assuming some form of democracy; without that they could just do as they pleased so long as they could get away with it). But if God made humanity, and if he made it to function in a particular way, then there is a best way to live. There is right and there is wrong, and one way will lead to a healthy society and the other will lead to an unhealthy one. If God made humanity, then it seems to me that human governments and leaders are, to a certain extent, mandated to lead humanity in the right way to live.
d) Human beings are responsible agents
Another way in which human beings image their Creator is in making significant moral choices. In the sphere of government, I think this should qualify what I have just said in point c. Governments cannot simply work out what is best for people and then make them do it. There has to be space for individuals to make real choices, even if that means choosing wrongly.
The combination of points c and d points to a system of law which sets limits on human freedom, but not unduly restrictive limits. Furthermore, as an expression of the rightness of the laws and as a foreshadowing of the fact that people will be held morally responsible by God for what they do with his laws, governments should rigorously enforce the laws that exist, punishing offenders. Laws which are unenforcable deny both c and d - they give the impression that there is no 'right', only what you can get away with, and they give the impression that you can get away with a lot and not be held responsible. So I would argue on this basis for a limited statute book, containing only what must be and can be enforced.