Many people have stickers about Jesus on their cars, but fail to use their turn signals. “I bet Jesus would have used His turn signals” is a saying that has been printed on many bumper stickers. The bumper sticker has been cited in print since at least 2001.
   
     
Google Groups: alt.gothic
What are the most important Goth values? 
BlackIce
4/18/01
(...)
Which reminds me, I really have to get one of those “Jesus Would Have Used His Turn Signal” bumper stickers.
   
Google Groups: alt.support.childfree
Couple of Good Ones, If I Do Say So Myself…
Rabbit
7/19/01
(...)
Years ago, I yelled at one, “I’ll bet Jesus would have used his turn signal!” I got the blank deer-in-the-headlights look. I still can’t decide if she’d forgotten she had the bumper sticker, or if she honestly didn’t know what that stalk on the steering column was for.
   
Google Groups: rec.arts.mystery
Falwell And Robertson
Melissa Cooper
9/15/01
(...)
> “I Bet Jesus Would Have Used His Turn Signal.”
 
28 July 2004, Detroit (MI) Free Press, “Turn-signal rant hits a nerve with readers” by Matt Helm, pg. 2B, col. 1:
Sue Steiger of Grosse Pointe Park: Mar car sports a bumper sticker that declares “I bet Jesus would have used his turn signals.” I have had four people ask me where I bought it or comment that it was a great sticker! The fact that my car carries this message makes me even more aware of using my signals for all turning and lane-change situations.
 
Google Books
The New Yorker
Volume 81, Issues 43-46
2006
Pg. 16:
Or maybe it’s his perspicacity in choosing bumper stickers printed with juicy, archetypal American aphorisms like “A leading cause of stress is reality,” “E.S.P. Extra Sexual Person,” or “I bet Jesus would have used His turn signals.”
 
Twitter
David Heinen Jr.
@LinkDJ
Best bumper sticker ever: I bet Jesus would have used His turn signals.
12:43 PM - 7 Apr 2008
   
Twitter
Maleficent 🦇
@malidragon
bumper sticker of the day: I bet Jesus would have used HIS turn signal
10:45 AM - 9 Jul 2008
   
Twitter
chriswarren22
@chriswarren22
bumper sticker on a dodge: I bet jesus would have used his turn signal
1:14 PM - 14 Oct 2008
   
Google Books
Spent: Sex, Evolution, and Consumer Behavior
By Geoffrey Miller
New York, NY: Viking
2009
Pg. 148:
Some bumper stickers that advertise different conscientiousness levels:
 
High Conscientiousness
• Get off the phone and crash already
• Jesus would have used his turn signals
 
Twitter
BetterAsAUnicorn 🦄
@dizzy_cricket
Ha!!  I got my bumper sticker! “I bet Jesus would have used his turn signals”
4:45 PM - 14 Apr 2018
 
Twitter
The Big Vic
@victoriainlyle
Replying to @_lola_bee
I bet Jesus would have used His turn signals.
9:53 AM - 22 Aug 2018