Why was "Under God" added to the Pledge of allegence?

An excerpt from Wikipedia:

"The Knights of Columbus in New York City felt that the pledge was incomplete without any reference to a deity. Appealing to the authority of Abraham Lincoln, the Knights felt that the words "under God" which were from Lincoln’s Gettysburg Address were most appropriate to add to the Pledge."

"It was a Presbyterian minister who made the difference in 1954 by preaching a sermon about Abraham Lincoln's Gettysburg Address. The minister was George MacPherson Docherty, a native of Scotland who was called to succeed Peter Marshall as pastor of the New York Avenue Presbyterian Church near the White House, where, in 1863, the same year as the address, Lincoln attended and even rented a pew. After Lincoln’s death, the pew that he rented became something of a national monument. It became customary for later United States presidents to attend services at the church and sit in the Lincoln pew on the Sunday closest to Lincoln’s birthday (February 12) each year."