Not the disproof of things seen.
Karen Armstrong writes at the Guardian:
The extraordinary and eccentric emphasis on “belief” in Christianity today is an accident of history that has distorted our understanding of religious truth. We call religious people “believers”, as though acceptance of a set of doctrines was their principal activity, and before undertaking the religious life many feel obliged to satisfy themselves about the metaphysical claims of the church, which cannot be proven rationally since they lie beyond the reach of empirical sense data.
Most other traditions prize practice above creedal orthodoxy: Buddhists, Hindus, Confucians, Jews and Muslims would say religion is something you do, and that you cannot understand the truths of faith unless you are committed to a transformative way of life that takes you beyond the prism of selfishness. All good religious teaching – including such Christian doctrines as the Trinity or the Incarnation – is basically a summons to action. Yet instead of being taught to act creatively upon them, many modern Christians feel it is more important to “believe” them. Why?
Follow the link to read how she answers the question.
We see the disconnect between professed belief and action in the evil and sordid deeds of those who loudly and publicly congratulate themselves on how “Christian” they are; they thereby discredit, not only their own creed, but all creeds.
Comes now the best argument that atheists can muster on the side of disbelief: the actions of “believers.”
Addendum, Later that Same Day:
Speaking of those who pray loudly in the public square, as the hypocrites do . . . . (Via the Booman.)