“Just because you go to church doesn't mean you're a Christian. I can go sit in the garage all day and it doesn't make me a car”

Though Keillor has been quoted on the internet and in print as having made this or a similar remark, such expressions have been made by others, and may have originated with Billy Sunday, who is quoted as having said "Going to church on Sunday does not make you a Christian any more than going into a garage makes you an automobile!" in Press, Radio, Television, Periodicals, Public Relations, and Advertising, As Seen through Institutes and Special Occasions of the Henry W. Grady School of Journalism (1967) edited by John Eldridge Drewry.
Disputed
Variant: Going to church no more makes you a Christian than standing in a garage makes you a car.

in Press, Radio, Television, Periodicals, Public Relations, and Advertising, As Seen through Institutes and Special Occasions of the Henry W. Grady School of Journalism (1967) edited by John Eldridge Drewry.

Homecoming saga, Earthborn (1995)

Source: The Robber Bride

Source: The Evil We Love

Source: Roger Biles, The human tradition in urban America http://books.google.pl/books?id=DqayY98DDDcC&pg=PA128&lpg=PA128&dq=church+garage+automobile&source=bl&ots=NMnjn43sFY&sig=I-YoAzHs5ChdCEE6lsOEK073WQY&hl=pl&sa=X&ei=sUsCT6-QE8vJsgb4qfmDAg&ved=0CCUQ6AEwAQ#v=onepage&q=church%20garage%20automobile&f=false (2002), p. 128.

A Fresh Look at Empiricism: 1927-42 (1996), p. 544
Attributed from posthumous publications