After tedious proceedings, during which Sir Henry Vane befriended him, Biddle was committed to custody and his Twelve Arguments, which he had now published, was ordered by parliament to be seized and burned by the hangman.
Notwithstanding this and the ordinance of the 2nd of May 1648, visiting denial of the doctrine of the Trinity with death, Biddle issued two tracts, one a Confession of Faith touching the Holy Trinity, and the other The Testimonies of Irenaeus, andc., concerning the one God and the Persons of the Trinity (1648).
This, however, was resisted by the army, and by many of the Independent parliamentarians; and after the death of the king, Biddle was allowed to reside in.