Everyone has some beliefs without scientific evidence. No one, no matter how skeptical, can take the time to prove EVERYTHING they believe, before they believe it. Now, religion is in an odd category, in that its not irrational, so much as it's arational (if that can be a word). The fact that it cannot be disproved in general principle may not be to its credit, but it's not actually a point against it either. For religious people, religion provides a community tradition, and potential answers to questions that science is not prepared to answer. It is also experiential. Somewhere, a poor person in dire straits has prayed and prayed for financial aid and just won a 10,000 dollar jackpot. Statistically seeking, it had to happen to someone, but is it really wrong for his family and friends to see this as evidence for the power of prayer?
The problem comes not from believing without proof. The problem is when one takes that and extends it into the realm of science. It's when one uses religion to replace science, instead of holding it alongside of science. A person who says dinosaurs never existed because the earth isn't that old is replacing science with religion, and yes, this definitely hinders scientific progress. A person who says that the bible is clearly wrong because the earth is older than it states is replacing science with religion and hindering their religious experience. Obviously we'd rather have person B in charge than person A, but these aren't the only two options. The third option is for a person to recognize that a timeless infinite God can spend only 6 days creating a much older earth because screw time anyway. This is a person that doesn't limit science with religion or religion with science. He has the potential of both a good scientist and a good priest, and as such, should he really be mocked for his faith?
Rhetorical question. This is Slashdot, so I already know the answer :P