--Excerpt from Spencer W. Kimball's "Miracle of Forgiveness" (pg. 127-128), quoting David Patten's account of meeting Cain:
I once asked someone why they believe in Mormonism. The response was an hour-long testimony which amounted to two primary reasons: upbringing, and comfort. This may be an over-simplification, but this is what I got out of it. And frankly, I was surprised that I didn't get the usual Mormon response of a "burning in the bosom." All in all, it was a good conversation and it is clear to me that this person gets great comfort from the idea of a god and an afterlife. I think I can appreciate this, despite not finding the argument very convincing. It may even be said that believing something because it makes you feel good is enough justification to hold the belief, if it is otherwise harmless. What harm could belief in Bigfoot cause? Or Santa Clause? Surely, these things bring people happiness or satisfaction.
A picture may be worth a thousand words, but a video is worth a thousand eye-witnesses. Objective evidence is almost always more compelling that subjective, anecdotal accounts. In recent decades, the use of DNA research has exonerated many people who had been convicted of murder and sentenced to death. Consequently, this has saved the lives of hundreds of innocent people. But how many more people have been wrongfully executed? Perhaps more importantly, how many murderers have slipped through the cracks of our justice system as someone else takes the fall?
Whenever an innocent person is convicted for someone else's crime, the real perpetrator walks free and can strike again. Contentment with a wrong answer generally means a halt on further investigation. This is the inherent problem with believing some false conclusion, even if you are comforted by it, as I'm sure the families of murder victims are comforted by the closure of a conviction.
In the Middle Ages, the Catholic Church suppressed scientific studies defying established dogma, which has likely set us back several centuries. Imagine the advances in cosmology and space travel we could be enjoying right now if various Popes hadn't killed and exiled scientists for heresy, like Galileo Galilei. Imagine the types of devices which could have sprung from Michelangelo, if science could have kept up with his vision. Imagine a working flying machine in the 1500's. Imagine Christopher Columbus teaching the Native Americans how to harness the power of electricity. Imagine an immunization shot for AIDS just a few months prior to Freddy Mercury's death. Imagine if all this had occured before the Inquisition! Where would we be if those in power, not being content with unjustified assertions, had put reason and evidence above faith and dogma?
If you believe that you really did see Bigfoot, then you will likely miss the fact that it was a man in a suit. If you believe that Santa gives you presents, then you might not appreciate all the work your parents put in to give you a memorable Christmas. Similarly, if you believe in the biblical creation story and that god created the universe--without any justification--then you might dismiss discoveries in physics which show how a universe can come from nothing, or how life can come from non-life through abiogenesis, or how evolution accounts for the diversity of the millions of species surrounding us.
Perhaps your unsupported beliefs are more comforting, but missing out on the majesty and awe of reality is tragic. Isn't it better to know the truth than to enable a delusion? Wouldn't you like to know if you are wrong about god? Wouldn't you like to be able support your beliefs with reason and evidence instead of inserting faith?
Here is Neil Degrasse Tyson discussing how Islam screwed up math and cosmology for the rest of us: