Of all the New Testament writings, it is the Fourth Gospel which raises in their most acute form the problems which were to vex the Church in the Trinitarian controversies of the third and fourth centuries. Many of the arguments set forth both by the heterodox and by their orthodox opponents consisted of exegesis of Johannine texts, and at the centre of the Monarchian controversies of the third century and the Arian controversy of the fourth was the question of the correct exegesis of John x. 30, I and the Father are one (ὡ ἕ ).