As far as I know the Catholic Church didn't forbid the use of forks, but many senior churchmen who had a foul and unholy lust for power and control over people opposed the use of forks.
Several Byzantine princesses who married into the families of Doges of Venice were accused of ultra luxurious practices like using forks.
Theodora was married to Domenico Selvo in Constantinople (1075) with full Imperial pageantry, and crowned with the Imperial diadem by her brother, Michael VII Doukas. Theodora brought a large Greek retinue to Venice, and rendered herself extremely unpopular because of her aristocratic bearing and haughty manner. What was then perceived as her Byzantine extravagance included the use of a fork, finger bowls, napkins, and sconce candles. The Dogaressa died of a degenerative illness, which was seen by the Venetians as a divine judgment for her "immoderate" lifestyle. There is an account of her lavish manners written by Peter Damian, the Cardinal Bishop of Ostia, entitled "Of the Venetian Doge's wife, whose body, after her excessive delicacy, entirely rotted away."1
It is not possible however for Peter Damian to have written anything about the marriage of Theodora and Domenico: their marriage took place in 1075 and Peter died in 1072. The same stories of Peter Damian have been equally attributed to Maria Argyropoulaina and Giovanni Orseolo: she the niece of the Byzantine Emperors Basil II and Constantine VIII and he the son of Doge Pietro II. Maria and Giovanni were married in Constantinople in 1005 or 1006. Both died in 1007 when a plague swept through the city-state. Peter Damian was born between 995 and 1007: he would have been, at most, 11 years old when Maria, Giovanni and their son arrived in Venice.
Maria Argyra or Maria Argyropoulina (Greek: Μαρία Αργυρή or Αργυροπουλίνα ; died 1007) was the granddaughter of the Byzantine emperor Romanos II and niece of the emperors Basil II and Constantine VIII.
In the Venetian Chronicle by John the Deacon, it is mentioned that Maria was the daughter of a noble patrician, called Argyropoulos, who was a descendant of the imperial family. This information is confirmed by the chronicle of Andrea Dandolo, who says that she was the niece of the emperor Basil II. As a member of the Argyros family Maria was also relative to the future Byzantine emperor Romanos III Argyros.
In 1004 Maria was married to Giovanni Orseolo, the son of the Doge of Venice Pietro II Orseolo, in the Iconomium palace in Constantinople with full imperial pageantry - the couple was crowned with golden diadems by Basil II. Maria brought to her husband great dowry, including a palace in the imperial capital, where they lived after the wedding. Basil also honored Maria's husband with the title of patrician.
At her wedding she used cutting edge, fashionable gold forks. But in the 11th century the fork was a controversial item. “She was roundly condemned by the local clergy for her decadence, with one going so far as to say, ‘God in his wisdom has provided man with natural forks—his fingers. Therefore it is an insult to him to substitute artificial metal forks for them when eating.’”
Before they left Constantinople, Maria Argyra begged the emperor for pieces of the holy relics of Saint Barbara, which were brought to Venice by her.
Maria Argyre and Giovanni Orseolo had a son, who was named after emperor Basil II.
In 1007 Maria along her husband and son died when plague swept through the city-state.
So some clergymen believed that:
‘God in his wisdom has provided man with natural forks—his fingers. Therefore it is an insult to him to substitute artificial metal forks for them when eating.’
I suppose that those same clergymen would forbid the peasants on properties owned by the church from using plows, and hoes, and other tools, and demand that the peasants do everything barehanded while working the land to support those clergymen.
The "byzantine" Theophanu (c. 955-990) Empress consort of Otto II from 973 to 983 and regent for Otto III from 983 to 990, was also criticized by some for her luxurious habits.
I believe that the "decadent eastern habits" of Theophanu and her son Otto III may have included - Gasp! Shudder! - using forks.