coupon for free pizza

I was looking at a coupon for a free pizza and reading the fine print to find out the catch. It didn't say anything other than that it couldn't be combined with any other offers or promotions. So it was a free pizza. How nice to get something actually for free! But then I thought to myself how strange that it said it couldn't be combined with any other offers. Who would need another offer when the item was free. 

I felt like God was saying, "see? That's how it is when you accept what Jesus did for you. It can't be combined with any other offers (works, other belief systems, etc). It stands alone because this free gift is all you need.