Logic. I used to teach someone who was better than me at maths. He would do a problem and if he came to the wrong conclusion he would ask me to see if I could work out what he had done wrong. The problem is that most of his logical working was different to my logic. He missed out bits, he did lots in his head, it took me a long time to make sense of his work because the way he thought logically was different to the way I thought logically.
The problem I have when people come to different conclusions to me is when I am told that what I think or believe has no logic. I admit occasional lapses into illogicalness, and when that happens I do tell myself off for it, or proclaim my fallible humanity that I cannot always be perfect. I have a problem though, when somebody tells me I am illogical, just because they disagree with me and assume I have not thought my deep held beliefs through. I would never believe in anything that I hadn't thought through and didn't make sense - I'm a mathematician.
I read recently an article in the Independent that is headlined 'Religious People are less intelligent than atheists....'. It can be found here. This hit home with me because I have been basically told I am stupid and illogical for believing in God - that I might as well believe in the flying spaghetti monster for all the sense it makes. When you read through the article you discover that actually the research is quite flawed and subjective - the researchers themselves do not take this as evidence that only 'stupid' people believe in God, but that there is more to it than that. They state the argument for more intelligent people not turning to religion as normally being that '...religious beliefs are irrational, not anchored in science, not testable....', but go on to conclude that there is something with more intelligent people that as they feel more capable in reason, that they do not want to lose control of what they can control - that there is an element of personal control in rejecting what they don't understand.
Now, I don't know whether that is true, and I am always suspicious when it comes to studies like this because of their subjectivity and the margins for error in statistical testing.... but there may be something in the fact that if we accept God as necessary and rational (which many intelligent people do), then that challenges our own human capabilities and often our perception of reason, and some of us find that a huge challenge because it does mean letting go of control.
For me it makes sense to believe in God. When I look at the world around me and in a way that is so finely tuned it makes even more sense. I came across an article by John Polkinghorne about The Anthropic Principle a while ago, which really excited me because it linked the beauty of Physics with the existence of God (worth a read). The more I learn about science, the more God makes sense.
I believe logic and reason do point to God. I value the work of intelligent Scientists who are also Christians that explain it in much better ways than I can (see The Faraday Institute for examples and more to read). So when I say I'm a Christian, I wish people would think and get to know me before they assume I'm illogical, because for me, it makes sense. Science and Religion are not in conflict and when we put our faith in human intelligence being the be all and end all of everything, I believe we miss out.
Every time I learn something new about the world, I cannot help myself but glorify God.