I came across a series by Greg Clarke written in response to the Atheist convention held in Australia early in 2010. His article on 'The Case for God' is very helpful (and a good length!)
Here are two (brief) arguments for God:
1. An originating capital-M Mind is the best explanation of why there is something rather than nothing, of why the universe is here at all. A more complicated statement that might also hold true is that our observance of the natural world leads us to conclude that it looks like a capital-M Mind was involved in its structuring, and furthermore, rationally, a capital-M Mind explains very well why the conditions of the universe are so finely tuned for life.
2. It is very hard to convince a human being, whether religious or an atheist, that the universe is without meaning, without values and without purpose. We are all pretty much agreed that it is full of these things: meaning (our lives matter), values (we can recognise with some finesse the difference between good and bad), and purpose (history is going somewhere). The hypothesis that there is a God does a better job of explaining these things than its alternative, the naturalist hypothesis, simply because with God these things are then real rather than illusory, as they are in the naturalist worldview. Real meaning, genuine values, lasting purpose. God is the best explanation of these elements of existence.Greg also makes the important point that very few people are ever argued into the kingdom of God. Much more helpful is an encounter with the Lord Jesus through the scriptures, however this kind of article can be helpful in laying down the philosphical background and framework that helps Christians (and not-yet-Christians) understand the philosophical underpinnings of faith.
It is certainly worth reading the rest of Greg's article, here: http://publicchristianity.org/library/response-to-global-atheism-conference-a-short-case-for-god.