New York-based syndicated entertainment columnist Earl Wilson (1907-1987) wrote in November 1964:
 
“WISH I’D SAID THAT: A man goes through three Santa Claus stages. First he believes in Santa; then he doesn’t believe in Santa; then he is Santa.”
 
The Santa Claus joke has been frequently told, always without any credit to anyone. A fourth stage—“he looks like Santa Claus”—has been infrequently added to the joke since at least 1989.
   
   
24 November 1964, Aberdeen (SD) American-News, “Earl Wilson’s New York,” pg. 4, col. 5:
WISH I’D SAID THAT: A man goes through three Santa Claus stages. First he believes in Santa; then he doesn’t believe in Santa; then he is Santa.
 
14 December 1964, Record-American (Boston, MA), “Man’s 3 Stages At Xmas Time by Bert Bacharach, pg. 32, col. 4:
THERE ARE three Christmas stages a man goes through: First, he believes in Santa Claus; then he doesn’t believe in Santa Claus; then he IS Santa Claus!
     
19 December 1980, Hartford (CT) Courant, “Today’s Chuckle,” pg. A1, col. 4:
A man goes through three stages: he believes in Santa; he doesn’t believe in Santa; he is Santa.
 
Google Books
The Best of the Good Clean Jokes
By Bob Phillips
Eugene, OR: Harvest House Publishers
1989
Pg. 138:
The four stages of man: He believes in Santa Claus, he does not believe in Santa Claus, he is Santa Claus, he looks like Santa Claus.
   
Google Books
14,000 Quips & Quotes:
For Speakers, Writers, Editors, Preachers, and Teachers
By E. C. McKenzie
Grand Rapids, MI: Baker Book House
1990, ©1980
Pg. 458:
A man goes through three stages: he believes in Santa Claus; he doesn’t believe in Santa Claus — then he is Santa Claus..
 
Google Books
19 December 1990, Princeton Alumni Weekly, pg. 18, col. 2:
Know the three stages of a man’s life? First, he believes in Santa Claus. Second, he doesn’t believe in Santa Claus. Third, he is Santa Claus.
 
Google Books
The 2,548 Best Things Anybody Ever Said
Selected and compiled by Robert Byrne
New York, NY: Fireside
2003
Pg. ?:
2.158
Three stages of a man’s life:
1. He believes in Santa Claus;
2. He doesn’t believe in Santa Claus;
3. He is Santa Claus.
—Unknown
 
Google Books
Snark! The Herald Angels Sing:
Sarcasm, Bitterness and the Holiday Season
By Lawrence Dorfman
New York, NY: Skyhorse Pubishing
2013
Pg. ?:
The 3 Stages of Man
He believes in Santa Claus.
He doesn’t believe in Santa Claus.
He is Santa Claus.
 
Google Books
Teacher’s Joke and Story Book
Collected by Stanley B Graham
Bloomington, IN: AuthorHouse
2016
Pg. ?:
Q. What are the four stages of man?
A. First, I believed in Santa Claus.
Second, I didn’t believe in Santa Claus.
Third, Now I am Santa Claus.
Fourth, Now I also look like Santa Claus.
 
Twitter
Shit Jokes
‏@ShitJokes
The four stages of life:
1. You believe in Santa
2. You don’t believe in Santa
3. You dress up like Santa
4. You look like Santa
3:13 PM - 12 Dec 2016