Wilson was absolutely an Elder in the Presbyterian church. By 1914 he had been an officer in the national church (southern Presbyterians) for 30+ years(clerk). His father had been a founder of the Southern Presbyterians.
Source ( http://www.history.pcusa.org/blog/2016/07/woodrow-wilson-and-great-war )
Wilson was also the President of Princeton, one of the most prestigious Universities in the country; founded and operated by the Presbyterians.
Source (https://en.wikipedia.org/wiki/Princeton_University). see history
Yes Wilson could have written such an essay 1914, either before or after July when WWI began. It was not a minority or even controversial position given our history and long precident set by our ongoing foreign and military policy.
Source (http://theweek.com/articles/627638/brief-history-american-isolationism ). See "How were the Founders isolationist?" & "What revived isolationism?"
I would argue that the essay in question written in 1954 criticizing the "moral optimism" of pre-WWI era America isn't accurate in framing that belief to 1914. America's "moral optimism" would be more accurately framed from George Washington's farewell Address in 1789 up through WWII, and was being heatedly debated in 1954 when theologian Gordon Clark published his topical essay.
Source (http://www.jhubc.it/admissionsblogdocuments/paper%20isolation%201.2.2012.pdf). see Part III: The Rise of Non-Interventionism and the Battle of ‘52
The US was an isolationist country free from foreign security treaties and guarantees from 1789 when George Washington famously counseled such, up through Dec 7th 1941.
Source (http://www.ushistory.org/us/17d.asp). See Paragraph 8.
When WWII began for instance the US had a standing army roughly the size of Belgium's,
and the US military survived a defunding vote by a single vote just months before Pearl Harbor in the US Congress.
Source (http://www.nytimes.com/1991/09/01/opinion/l-the-vote-that-saved-the-army-in-the-days-after-pearl-harbor-028191.html) See: The Vote(august 1941)That Saved the Army in the Days After Pearl Harbor -
Now that's some "moral optimism".
The essay being discussed written in 1954 is part of the debate the nation found itself in after the Korean War started and we went to war in 1950 with a small fraction of the forces we commanded five years prior at the end of WWII. That fraction being poorly trained, and poorly equipped when the war began.
The US largely demilitarizing after WWII and thus was rather hard pressed to come up with enough forces to repel N. Korea's advances.
Source (https://en.wikipedia.org/wiki/Korean_War#U.S._unpreparedness_for_war) see - U.S. unpreparedness for war
The debate framed by this Essay against "moral optimism" is one which resulted our status today and the most militarized country in the history of the world... One which spends more on it's self defense than the next greatest 8-10-12-18 largest militaries depending upon which year in the last decade you've asked that question(currently ).