"Thanks God" joke

A man lost in the dessert for 2 weeks, finally spots a small oasis and is able to just crawl up to it
before collapsing. The resident missionary finds him just in time, and slowly nurses him back to
health.
Fully recovered the grateful guy wants to get back to civilization and asks his benefector, "Could I
borrow your horse, and give it back later, or possibly leave it for you in the next town?
The missionary says, "Surely, you may, but there's one special thing about my horse. Instead of
' giddiup' you have to say `Thank God' to make him go... and you have to say' Amen' to make him stop.
He won't respond to `whoa.'"
Not paying all that much attention, our hero says, "Sure, OK," and he mounts the horse and starts off
with an initial "Thank God." The horse starts walking slowly when our impatient hero repeats, "Thank
God, thank God," and the horse starts trotting. Encouraged by this, the guy then shouts, "Thank God,
thank God, thank God" and the horse just takes off at full tilt.
However, pretty soon our hero sees a cliff coming up ahead, and starts doing everything he can to
make the horse stop.
"Whoa!!... Stop!!... Hold on!!" he screams - but to no avail. The horse doesn't stop! Finally, he
remembers what the missionary said and shouts, "Amen," and the horse slows just in time, just inches
away from the precipice. Relieved with still being alive, our hero leans back in the saddle, wipes
his brow and audibly sighs, "Thank God."