Minority denominations with fewer than 3,000 members would not be allowed to legally register, under a planned amendment to the country's Religious Denominations Act.
Mark Jeffrey, a missionary in Exeter who regularly visits Bulgaria with his wife to preach in churches, said the clause could be used to target smaller Protestant churches which are already registered.
Mr Jeffrey, who first visited Bulgaria ten years ago, told Premier: "It will make it impossible to continue legally.
"It will basically take the Church back to Communist days... the Church will have to go underground which most people would have thought would be impossible to see in modern Europe."
BULGARIA: Bulgarian lawmakers concede some restrictions in a new Religion Denominations Act after international pressure and intensive protests. A new constraint however threatens the legal existence of many denominations. An in-depth analysis:https://t.co/htueHKC89T
— Evangelical Focus (@Evan_Focus) November 22, 2018
Following objections and protests from various faith groups in Bulgaria, the proposals - which are intended to tackle radical Islam - have already been watered down. The Baptist World Alliance and the World Evangelical Alliance have been among those to highlight their concerns.
It is understood the original version would have prevented foreign church leaders from conducting religious services unless they had been vetted by Bulgarian officials. Bulgarian church leaders trained abroad would also have been affected.
The first reading draft would have also banned unnamed donations to Bulgarian churches from foreign entities. It would have also stopped Protestants running theological colleges and meeting outside of designated church buildings.
It is believed a second reading draft removes such restrictions but other limitations remain on the table. For example, foreign religious leaders arriving in Bulgaria for a short-term visit (fewer than three months) would have to notify officials.
PHOTOS: Christians rallied in #Sofia (Bulgaria) on November 18. It is the second Sunday of peaceful demonstrations against a new religion draft law that could severely restrict freedoms and rights of minority faith confessions. https://t.co/cWEdYCUhME pic.twitter.com/v5ila8xKw5
— Evangelical Focus (@Evan_Focus) November 21, 2018
Politicians are due to vote on the proposed amendment in the coming days.
Religion was discouraged and often persecuted in the Soviet Union and nearby socialist satellite states prior to the collapse of the Iron Curtain.
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