I hate to bring up an old can of worms, but I was thinking about this thread this morning, and it dawned on me to research the name "McGrea". It turns out that "Mc
Grea" is in fact the same name as "Mc
Crea". They are just variable spellings. In fact, according to this website, are stem from the same name.
http://www.surnamedb.com/Surname/McGraw
Therefore, the name "McGreachery" could very well still mean "Dear Son of God". In fact, the counter-theory for this card was that the confusion of the card was that it was really intended to write McGeachy, after Jack McGeachy of the Indianapolis team.
But the thing is that Jack McGeachy's name also means "Son of God"
McGea - son of God
Chy - child
Gaelic was a very rough language with many different spellings. That's why you are seeing variations of this word "Crea" in the form of "Gee", "Kee" (as in D. Mc.Kee), Crea, Grea, Graw, etc.
In light of this discovery, it is very unlikely that the name "McGreachery" was a misspelling. My view is that it was probably done intentionally. Also, when you take into context the player involved, the card, and the name on it, was almost certainly a joke. Deacon White was a very well-known player - the greatest third baseman of the 19th century. Goodwin and Co. took seven other photos of Deacon White - they must have had a very good idea of whom he was. Remember, Deacon White had been in the league for over fifteen years by that time. He was also known for his wacky religious beliefs in an era, like today, of growing atheism. Also, keep in mind that most people were given a classical education in latin and french back then, and the word for God (crea/grea/graw/cray, however you want to pronounce it) is a vary basic word.
Knowing all that, I just find it very hard to believe that the McGreachery name was written as some sort of accident. One of the reasons why we had the confusion between C and G for the card is that they look alike. They must look alike because those two letters were used almost interchangably in ancient times. So in retrospect, I don't believe that the fact that the name is McGreachery instead of McCreachery really makes it a flawed theory after all.