Josefo, en su obra Antigüedades judías, al relatar su muerte le denomina «el hermano de Jesús, llamado Cristo, cuyo nombre era Santiago». En el Nuevo Testamento, es referido entre los «hermanos [de Jesús]» en Marcos 6:3, Mateo 13:55 y Hechos 1:14.
Pablo de Tarso, en su epístola a los gálatas (Gálatas 1:19), escribe sobre «Santiago el hermano del Señor». El epíteto fue conservado en la tradición cristiana; en el cristianismo oriental (Liturgia de Santiago) se le denomina Iákōbos Adelphotheos (Iάκωβος ο Αδελφόθεος): «Santiago, el hermano de Dios».
No obstante, Tabor sostiene que Santiago es identificado como hijo de María en Marcos 15:47 y Marcos 16:1. Su teoría supone que Santiago el Justo es hijo de Cleofás y María, la madre de Jesús.[15]
Refoulé, 1995, p. 89: «For the exegete and the historian, the brothers and sisters of Jesus are in all probability his blood brothers and sisters»;Painter, 2001, p. 57: «James was the younger brother of Jesus, born to Mary and Joseph subsequent to the birth of Jesus»;Myllykoski, 2006, p. 80: «The vast majority of scholars think that Helvidius was right in his claim that the brothers and sisters of Jesus were children of Joseph and Mary, born after Jesus»;Casey, 2010, p. 144: «Christian tradition has supposed that Jesus’ brothers and sisters were not born of Miriam [...]. We must prefer the evidence of Mark: Miriam had several children». Painter, John (2001). «Who was James? Footprints as a Means of Identification». The Brother of Jesus: James the Just and His Mission. pp. 10-65.Myllykoski, Matti (2006). «James the Just in History and Tradition: Perspectives of Past and Present Scholarship (Part I)». Currents in Biblical Research5: 73-122. doi:10.1177/1476993X06068700.
Myllykoski, 2006, p. 80. Myllykoski, Matti (2006). «James the Just in History and Tradition: Perspectives of Past and Present Scholarship (Part I)». Currents in Biblical Research5: 73-122. doi:10.1177/1476993X06068700.
Myllykoski, 2006, p. 89. Myllykoski, Matti (2006). «James the Just in History and Tradition: Perspectives of Past and Present Scholarship (Part I)». Currents in Biblical Research5: 73-122. doi:10.1177/1476993X06068700.
Myllykoski, 2006, p. 90. Myllykoski, Matti (2006). «James the Just in History and Tradition: Perspectives of Past and Present Scholarship (Part I)». Currents in Biblical Research5: 73-122. doi:10.1177/1476993X06068700.
Myllykoski, 2006, p. 81. Myllykoski, Matti (2006). «James the Just in History and Tradition: Perspectives of Past and Present Scholarship (Part I)». Currents in Biblical Research5: 73-122. doi:10.1177/1476993X06068700.
Myllykoski, 2006, p. 85. Myllykoski, Matti (2006). «James the Just in History and Tradition: Perspectives of Past and Present Scholarship (Part I)». Currents in Biblical Research5: 73-122. doi:10.1177/1476993X06068700.
Myllykoski, 2006, p. 112. Myllykoski, Matti (2006). «James the Just in History and Tradition: Perspectives of Past and Present Scholarship (Part I)». Currents in Biblical Research5: 73-122. doi:10.1177/1476993X06068700.
Myllykoski, 2006, p. 107. Myllykoski, Matti (2006). «James the Just in History and Tradition: Perspectives of Past and Present Scholarship (Part I)». Currents in Biblical Research5: 73-122. doi:10.1177/1476993X06068700.
Myllykoski, 2007, p. 84. Myllykoski, Matti (2007). «James the Just in History and Tradition: Perspectives of Past and Present Scholarship (Part II)». Currents in Biblical Research6: 11-98. doi:10.1177/1476993X07080242.