Answer: President Dwight D. Eisenhower
Full paragraph for further info:
On February 1, 1953, just 10 days after his inauguration, President Dwight D. Eisenhower was baptized at the National Presbyterian Church in Washington, D.C. at the age of 62. Though the baptism ceremony itself was private, Eisenhower made every effort to place faith at the center of national life during his years in office. Eisenhower remains the only president ever to have been baptized while in office, and his work to link faith and American identity has influenced political debate in the country for half a century since.