Rational and logical thought are only as perfect as the underlying data

Not at all. Thought does not necessarily require data. If I claim that my atheism is based on rational thinking, what I am saying is that everything in human experience, apart from this God chappie, follows the laws of physics, as far as we know. For notions put forward to us, it is our instinct as human beings to require evidence and to seek it out. We call it doing science. Believers in God have characterised him, without evidence or justification, as being beyond science. He's untouchable because you say he gets a bye when it comes to what everything else in the universe has to do, obey the laws. On top of all that he must be far more complicated than the most complicated thing that Einstein or Hawking or any of our other great thinkers has ever contemplated. I'd say it was rational to reject God on these bases. Highly rational, bearing in mind, of course, that rational doesn't mean right. Now the converse, taken away from the context of the comfort that believers clearly derive from their faith, must be that it is highly irrational to believe in God. It's a hard case to put, because people who believe in God often believe because they have been told to, or have just lived their lives accepting with apathy what others around them believe. Then there's the nice biblical yarns, the family thing, the long tradition, the ceremony, the highly-persuasive religious music and beautiful architecture. You could make a good case for saying that it's rational to go along with all that. Once you're in it, it's certainly more comfortable and, dare I say, personally beneficial to stay in it (and not to do too much thinking, something organised religion likes). But all that aside, if you take thought and weigh up in a detached way the pros and cons, and you still come out believing, you are indeed being highly irrational. Which doesn't mean the same thing as wrong, though you probably are.