Bishop Dónal Mac Keown claims these services are being carried out by an ultra-conservative splinter group of the Society of Pius the Tenth known as SSPX Resistance.
The Society of Pius the Tenth was founded in 1970 as a traditional Catholic reaction to the reforms of the faith brought about by the second Vatican council.
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They are best known for retaining the Tridentine mass – commonly known as the Latin mass.
Bishop McKeown says the church does not approve of SSPX Resistance, urging local Catholics to remain “steadfast”.
SSPX Resistance are certainly uncompromising traditionalists, but the splinter group has been accused of antisemitism and having ties with the far right.
Its founder held deeply antisemitic view and was a convicted Holocaust denier.