The Knights of Columbus are Responsible--The Catholic Connection
How the words "UNDER GOD" came to be added to the Pledge of Allegiance to the Flag
The Pledge of Allegiance to the Flag of the United States originated on Columbus Day, 1892. It contained no reference to Almighty God, until in New York City on April 22, 1951, the Board of Directors of the Knights of Columbus adopted a resolution to amend the Pledge of Allegiance as recited at the opening of each of the meetings of the 800 Fourth Degree Assemblies of the Knights of Columbus by the addition of the words "under God" after the words "one nation". The adoption of this resolve by the Supreme Board of Directors had the effect of an immediate initiation of this practice throughout the aforesaid Fourth Degree Assembly meetings
Later it was put before Congress and in 1954 it was adopted.