The disputed words [i.e. «υἱοῦ θεοῦ» ("Son of God")] are enclosed in square brackets in UBS4 and NA27 and they are omitted from SBLGNT. Most modern translations and commentators include the words. Recently, however, several scholars, most notably Peter Head, Bart Ehrman, and Adela Yarbro Collins, have argued for the shorter version of Mark 1:1. Perhaps the strongest argument in favour of the short reading, which was first brought forth by Jan Slomp and subsequently developed by Head and Ehrman, is the unlikelihood of an accidental omission in the opening words of a work. [...]
Among English versions only the 1946 edition of the Revised Standard Version of the New Testament, the New World Translation, and the Today’s New International Version of 2002 have the shorter version (the longer version was subsequently restored in the Revised Standard Version 1952, and the New International Version 2011). In his survey of available commentaries (in 1991), Peter Head found that practically all English commentaries included the words, whereas Continental commentaries differed widely. See Peter Head, ‘Text-Critical Study’, pp. 621–2; cf. Greeven and Guting, Textkritik, p. 44. The situation after 1991 is basically the same, although a few American commentators have recently argued for the short reading, e.g. Joel Marcus, Mark 1–8: A New Translation with Introduction and Commentary (AB 27; New York: Doubleday, 2000), p. 141; Adela Yarbro Collins, Mark: A Commentary (Hermeneia; Minneapolis: Fortress Press, 2007), p. 130.
"The ‘Son of God’ was in the Beginning (Mark 1:1)"
"Η φράση 'Υιός Θεού' υπήρχε Εξαρχής (Μάρκος 1:1)",
Journal of Theological Studies,