From Mark Dever's 9 Marks of a Healthy Church:
One time at Cambridge I was talking with a Lebanese Muslim friend of mine about a mutual friend who was a fairly secular Muslim. My friend wanted him to embrace a more faithful Muslim lifestyle, and I wanted him to become a Christian. So, in a strange way, he and I had something in common. We were both concerned about this friend, though we had very different solutions for his problem. We commiserated on the difficulty of living in a secular British culture. Then my friend remarked on the corruption of this Christian country.
I responded that Great Britain is not a Christian country, that in fact there is no such thing as a Christian country. That, my friend said, quickly seizing the opportunity, is the problem with Christianity compared to Islam. Christianity does not provide answers and guidelines for all of the complexities of real life, he maintained. It has no overarching sociopolitical pattern to offer people for the real questions they come up against. I responded that that is because of Christianity's realistic portrayal of the human condition. He asked me what I meant. I said that, to speak frankly, Islam is shallow in thinking that the human problem is simply a matter of behavior. According to Islam, it is merely a question of the will. But Christianity, I said, teaches that there is a much deeper problem, and this is a more accurate understanding of the human situation. Christianity includes a frank admission of human sinfulness not merely as an aggregate, a collection, of bad actions, but as an expression of a bad heart, a heart in rebellion against God. Christianity recognizes our problem as a matter of character, of human nature. Christianity has nothing that could be recognized as a comprehensive political program because we don't think that the real human problem can ultimately be dealt with by political power.
To make it clear, I said to my friend, "Look, I could put a sword to a person's throat and make him at least a sufficiently good Muslim."
He agreed that that was true.
"But," I continued, "I cannot put a sword to a person's throat and make him a Christian. Becoming a Christian is not merely a matter of your doing this and not doing that, or of your following that law and not doing that thing. To be a Christian is to have your life transformed by God."