*8”If they [the brethren of the Lord] had been Marys sons and not those taken from Josephs former marriage, she would never have been given over in the moment of the passion [crucifixion] to the apostle John as his mother, the Lord saying to each, Woman, behold your son, and to John, Behold your mother [John 19:2627), as he bequeathed filial love to a disciple as a consolation to the one desolate” (Commentary on Matthew 1:4**
Why could that not have been a statement for John, not Jesus’ mother?
The argument suggests that Mary must not have had sons, or else Jesus wouldn’t assign her to John.
But if that argument is accurate, than was John born without a mother, so that Jesus had to give him one?
John took her to his home that same hour. Remember that Mary, Joseph, Jesus (and the rest of the offspring) were living in Nazareth right up to the beginning of Christ’s ministry. So, should they have still been living in their own homes in the area, Mary was going to have a long hike back. Remember that John, one of the sons of Zebedee, was called by Jesus at the beginning, while mending fishing nets at the Sea of Galilee. Also remember, that later at the trial of Jesus, John is said to have been known to the high priest in Jerusalem. Could it be that John had been living in Jerusalem, but lived part time with his parents in Capernaum as a fisherman?
Logistics say that they didn’t head back to Galilee that same hour, for they were present for the resurrection events three days later. Galilee is about 70 miles, as the crow flys, from Jerusalem. Over and around the rough terrain, it was likely over 80. At least 160 miles round trip. John apparently had a home in Jerusalem, or in the immediate area; and took her in at the Lord’s command. Simple as that.
The above is my opinion; just as your RC teachers use their opinion to build a case for Mary doctrine.
Also too, when Jesus gave his mother Mary to John, at the foot of the cross, that in turn made her the spiritual mother of ALL Christian believers.