Brian, the Bible itself calls for tithes, 10%,etc...I'm sure you're aware of this.
It's not enforced though, my father in particular used to struggle trusting Him with our finances and thus did not give much toward the Church.
That was a while ago, today he gives of his earnings and is the better for it.
Note, we are not wealthy, far from it, yet we are relatively content.
Besides, all is the LoRD's anyways, so it's fully within his "rights" to ask for a little back.
Sometimes even to live is an act of courage. ”Seneca