I reckon he was trying to say that if god only gets 10% then who is she to think that she is better than god and deserves 18%.
people like him who worship money give all christians a bad reputation.

“I thought the note was insulting, but it was also comical," the waitress, whose name is Chelsea, told Consumerist. "I posted it to Reddit because I thought other users would find it entertaining."
Apparently once the receipt hit the Internet, the supposed pastor forgot the Golden Rule of “love thy neighbor” and called the Applebee’s where Chelsea works to demand that she and all management involved be fired.
The pastor is not the first to write an excuse on a receipt to get out a hefty tip on a bill. A single mom recently opted out of a tip on a restaurant bill for close to $140 by simply writing, “single mom sorry.” Another Applebee’s customer in Edison, NJ, wrote “stop eating bitch!” on the receipt rather than leave some gratuity for his server.
