David Barton and Tithing: I Wonder What's On Ted Cruz's Odometer?

On his Foundations of Freedom program, president of one of Ted Cruz’s Super PACs David Barton told Glenn Beck that God will bless you if you tithe, including — as an illustration — the provision of a car that run for 200,000 miles. He seems to have a similar view of the subject as does Gateway Church pastor Robert Morris and Ted Cruz’s father, Rafael. Watch this clip provided by Right Wing Watch:
I would like one of the Cruz inner circle to explain how Ted Cruz can hope to be blessed when he has admitted that he doesn’t tithe. The elder Cruz and Barton earnestly teach tithing as a prerequisite to being blessed. Since Cruz hasn’t (doesn’t?) tithed, how can Beck and Barton claim Cruz is the man God sent to be president?