Gardner was born on July 25, 1883, in Buffalo, New York, the son of Frederick A. Gardner and Sarah Jane McConnell and the fourth of five children. He was educated in Catskill, New York and later at St Stephen's College in Annandale-on-Hudson, New York from where he graduated in 1906 with a Bachelor of Arts. He then worked as a teacher in private schools between 1906 and 1908, after which he became a student at the General Theological Seminary in New York City. He received his Master of Arts from St Stephen's in 1910 and his Doctor of Divinity in 1923. he was awarded a Doctor of Sacred Theology from General in 1937, Rutgers University in 1938 and Philadelphia Divinity School in 1939.
