When a Christian carpenter living in a certain middle eastern country, knowing that Christian activities are punishable by chopping off a hand, continues to demonstrate he is Christian anyway. It's just not logical, most say. It's just plain stupid, many say.
When a mother of a slain teenaged boy, ravaged with grief, seeking consolation in the Bible, reads Mark 11:25 and decides that despite the feelings in her gut, she will visit the jail in which her son's murderer is locked up, and to forgive him face to face.
When a young girl who has been saving up her allowance for a new ipod, hears that one can find God in Charity, and decides to give half that money to a fundraiser for a country that was recently hit with a Typhoon.
It's not sensible. It's not rational. It could be called 'just stupid'.
Faith puts hope in something greater than personal safety. Greater than revenge. Greater than having the latest electronics. Faith puts hope in God, and in so doing, discovers something, no, someone, that could not have been imagined prior to taking that step.
Parents have a sense of this. Prior to having children, if the adult is not prone to cooing up to babies, and sees kids as being a vacuum cleaner sucking up a person's time, money, and sanity, it might seem not rational to want to give up your personal time and freedom for the sake of a dependent leach (sorry kids, I don't mean you... making a point here).
But after having children, that very same adult experiences a certain fullness of life that can't be described or appreciated before taking the leap.
Taking an action of faith in God is similar. Something very real happens that adds color, fragrance, and life to your time on earth. You encounter a great friend who gives you comfort and solace that not even the best Swiss dark chocolate can provide. And you find He's real. Blows your mind.