the concept of tithing is to give back to god 10% of what you make because everything you make was given to you by god and it's a sign of thanks and appreciation for what you have earned or something. Plus, there are 2 types of tithing: 1st one is thanksgiving tithe, which is just spare change you might have on you at the time, and the 1/10 tithe, which is supposed to do at the end of the month or something. Plus, tithing has more practical purposes such as paying for the rent for the building, utilities, foodstuffs, etc.