Members of the congregation at Our Lady of Peace Catholic church in Burnham, Buckinghamshire, put Gary Trotter, 41, in a headlock before dragging him out. One worshipper shouted that he wanted to "ethnically cleanse" him.
The trouble began when Mr Trotter, who objected to his son Luke becoming a Catholic, approached the priest who conducted the service, Fr Tony Brennan, to hand over a letter and explain to worshippers what he was doing. It was then that members of the congregation pounced on him.
Fr Brennan tried to intervene but more churchgoers leapt on Mr Trotter. Women burst into tears and a man threatened to kill Mr Trotter, who claims his son's school is indoctrinating him into the Catholic faith against his will.
He said Luke had "told me on several occasions he did not want to take part in the church service and I have tried for several months to tell the school and the priest about this." Luke is at Our Lady of Peace School in Burnham. His mother, Jacqueline Corriette, who is separated from Mr Trotter, had consented to his taking part in the service.
A spokesman for the Northampton Roman Catholic Diocesan Trustees said that they had sought legal advice before the ceremony. "Luke's presence at the school and the ... wishes of his mother were reasons enough for accepting he should make his First Holy Communion."Reuse content