Which reminds me of a story about a missionary who was watching a group of natives who were killing hogs. The natives were cuting off the hogs’ tails and throwing them in a pile. The missionary asked one of the natives why they were doing this, he replied, “The meat is for us, the tails are for our gods.”
Unfortunately, for any number of reasons some Christians do the same thing. They keep most of their money for themselves and give God the leftovers, if anything.