I have found the following information. It apears to be your grandmother's brother, although the name of his father differs from what you posted:
Name: John Shnurer
Last Residence: 76110 Fort Worth, Tarrant, Texas, United States of America
Born: 20 Jul 1897
Died: Nov 1976
State (Year) SSN issued: Pennsylvania (1956-1958
He is included in family trees posted on Ancestry.com. Posted information for him in family trees:
Name: John F. Shnurer
Birth: 20 Dec 1897 - Ukraine
Parents: John Shnurer, Victoria Kopestensky
Spouse: Mildred Mutchko
This man is listed as Reverend, a religious leader, which fits with your information of him becoming a priest. His birth place is listed as Premysl, Ukraine by one person.
Reverend John Florian SHNURER, wife Mildred, was the rector at St. Mary's Ukrainian Orthodox Church in the city of Herkimer, New York, in 1940.
In 1937 they lived in the state of Connecticut. John went by the name of J. Florian SHNURER in some records.
Here is their information from the 1940 census:
1940 New York State, Herkimer County, Herkimer town
Sheet 1A April 11
address appears to say: 33a More Avenue
SHNURER, John J., head, male, white, age 41. Birthplace: (appears to say Eukrania with something else written), residence in 1935: Connecticut. Has filed first papers for citizenshiip. Occupation: Priest, Ukranian.
SHNURER, Mildred, wife, female, white, age 31, born Pennsylvia.
SHNURER, Florian, son, male, white, age 11, born Pennsylvania.
SHNURER, Irene M., daughter, female, white, age 6, born Connecticut.