I like this way of thinking. Sometimes I have phrased it this way:
If a believer is wrong, she will never know.
If a believer is right, she will reap a great eternal reward.
If an unbeliever is right, he will never know.
If an unbeliever is wrong, he will reap a great eternal disaster.
Now, assign whatever probabilities you like to the proposition of who is right or wrong...
Then compute the expected value of taking one of these positions.
For the believer it is always positive.
For the unbeliever it is always negative.
Absolutely. And when I share my faith it is not in a way to be morally superior, but because I do care where people may end up eternally. It would actually be more unloving to never ever share my faith. But it is not my job to try to force someone to believe, but plant a seed of thought.
I enjoy learning about all faiths and respect many different thoughts and beliefs, but feel certain religions receive a terrible reputation based on the actions of a select few.