While a student at
Carmarthen Grammar School in 1743, Williams was converted after hearing a sermon by
George Whitefield. In 1770 Williams began to publish copies of Welsh language bibles at an affordable price, with commentaries on each chapter. The commentaries assisted in avoiding the claim to a monopoly over the right to publish the Welsh Bible which was asserted by the Royal Printer and the Universities of Oxford and Cambridge. The first edition of Williams' Bible was printed by John Ross and published in Carmarthen in 1770. It was the first ever publication in Wales of the Welsh Bible. It sold out in the same year. There was a demand for many more editions. In due course Williams produced thousands of copies of Welsh language bibles and 'Beibl Peter Williams' remained popular in Wales throughout the nineteenth century. In 1773 Williams published a biblical concordance in the Welsh language (the
Mynegeir Ysgrythurol) which greatly assisted study of the Welsh Bible. Williams was also a writer and a poet. He edited a volume of Welsh hymns in 1759 and published Hymns on Various Subjects in 1771. In 1771 he was the first translator into English of the popular hymn
'Guide me, O Thou Great Jehovah' from the original Welsh of Williams Pantycelyn: the first verse of Peter Williams' English translation is still sung today. Williams' commentary on John i.1 led to suggestions that he sympathized with
Sabellianism. The controversy sharpened in 1790 when Williams published a Welsh language bible with a Welsh translation of the biblical annotations first published in 1647 by the English Puritan minister
John Canne. In 1791, the matter came to a head at a Methodist 'Sasiwn' (Association meeting) at
Llandeilo and Williams was expelled. == Death ==