The purpose of tithing is to teach us to always put God first in our lives. God doesn’t need our money. He wants what it represents, our faith in God, our putting Him first in our lives and our thankfulness for what He has given us.
And here is the promise: “Then your barns will be completely filled, and your vats will overflow with new wine.” You and I are called to give back to God with thanksgiving, as we do it is a demonstration of our faith in God. God says he will provide all that you need; you only have to put Him first.