True. And when the news was released that he had won the election, his Mother wept and lamented, “To think that he would stoop from being a Minister of the Gospel to being President.”
According to the Garfield biography on Wikipedia, after graduating from Williams College, "Garfield ruled out becoming a preacher". The rest of the biography doesn't seem to leave any time for his ordination.
This document from 1904 explains:
"In the early days of the Churches of Christ on the Western Reserve--and probably this was true elsewhere--it was not a difficult thing for a young man to enter the ranks of the disciple ministry, if he was a Christian, had fair gifts of body and mind, knew the alphabet of the gospel of Christ, was willing to study and had a desire to preach, he was encouraged to preach. Very few of the early disciple preachers ever "studied for the ministry," or were ever "ordained" to the ministry, in the modern, ecclesiastical sense of those terms. Hence in the commonly accepted sense he was never a preacher or minister; but this may also he said of hundreds of other preachers in the Churches of Christ, at that time, before and since. He did, however, "preach the Word." He did hold "revival" or protracted meetings and often with great success."