I think it is both rational and irrational.
The people that I know who believe in God say that their lives have improved because of their belief. Doing something that improves the quality of your life is a rational thing to do.
God’s existence has never been proven nor disproven so one has to believe in God. Belief isn’t rational. I consider beliefs to be pre-rational, because they are the axioms from which we build our arguments.
Irrationality shouldn’t be taken as a criticism. Emotions are irrational. They tell us what we value. If we don’t value something, we don’t get emotional about it.
Creativity isn’t rational. Much of the good in the world is the result of someone’s creativity.
To summarize, faith itself isn’t rational. Choosing to have faith because it improves your life is a rational choice.
©2016 Stephen L. Martin
Photo: Marble bust of Aristotle