The pastor at church told this story today:
There was a man in Houston, Texas that got a letter in the mail from his church (or maybe just a church in the community). The letter stated that the church was trying to retire its building debt, and was seeking donations. The letter stated that if you sent in a gift of $76 or more, God would bless you with a reward worth triple that amount. The man wrote back to the church, without enclosing a check, writing the following:
"Dear Pastor ______,
If you really believe what you wrote in the letter, why don't you write me a check for $76? Then your gift would triple, which would help the church pay off its mortgage."
Though this is funny, the "give X amount and God will double, triple, etc." message is a very popular, yet misguided doctrine taught mostly in the Word/Faith sector of Christendom (a sector to whom many popular TV evangelists belong). Many, but certainly not all, "non-denominational" churches are usually of the Word/Faith movement. From personal observations, it seems like the goals of these churches are more about building the next mega-complex or exalting the pastors' authority and wallets than solely bringing people to Christ and providing them with a thorough study of the Bible. That does not mean that these churches do not teach the essential elements of the Gospel and that the parishioners are not saved. However, when a pastor's primary focus is having the next mega-church and "living large" someday instead of bringing the visitors they come in contact with on any given Sunday to Christ, the message takes the risk of being deluded in order to bring in the number of people needed to achieve those goals.
More on this later...