Page 6 Requirement Tithing LDS
The concept of tithing comes from the Old Testament. It spoke about giving a tenth of your income and it is supposed to be joy to give. That's not so much the case in today's materialistic world. Also, the Old Testament was superseded by the New Testament, so Christians are merely urged to give as they can.
Of course, this is about the LDS. They take their tithing seriously and draw inspiration from the Old Testament. I also understand they do a lot of good with the money they receive. Not only do they spread their word, which may or may not be good depending on your outlook, they go to many impoverished areas and provide improvements, like schools and clean water, with that money.
I'm not a Mormon, but I think they do more with the money they receive than say the Catholic Church does with its vast riches, which it's loathe to give back to the needy. So, at least they are giving back with this money.