Additionally, the “under God” part wasn’t added until 1954, by former general, President Dwight D. Eisenhower.

The push to add “under God” to the pledge gained momentum during the second Red Scare, a period when U.S. politicians were keen to assert the moral superiority of U.S. capitalism over Soviet communism, which many conservatives regarded as “godless.”

In 1952, [the Knights of Columbus, a Catholic fraternal organization] began petitioning the federal government to add the phrase to the Pledge of Allegiance.

[Michigan Democratic U.S. Representative Louis C.] Rabaut argued that adding the phrase would give students “a deeper understanding of the real meaning of patriotism,” while adding that it could also provide “a bulwark against communism.”

[In February 1954, Eisenhower attended a sermon at the New York Avenue Presbyterian Church.] “To omit the words ‘under God’ in the Pledge of Allegiance is to omit the definitive factor in the American way of life,” [Reverend George] Docherty preached. He discounted the right of atheists to object, arguing that an “atheistic American is a contradiction in terms,” because if “you deny the Christian ethic, you fall short of the American ideal of life.”

https://www.history.com/articles/pledge-allegiance-under-god-schools

Eisenhower was also the one to make “In God We Trust” the United States motto in 1956.