The Gospel of Mark says that, during Our Lord’s public ministry, some “people” accused him of being “beside himself.”

Mark 3:21 (RSV) And when his family heard it, they went out to seize him, for people were saying, “He is beside himself.” (Other translations with “people” include NRSV, NEB, Phillips, Moffatt, TEV)

Mark 3:31 And his mother and his brothers came; and standing outside they sent to him and called him.

Note the italicized word “people” above. This is key to understanding this incident. There is dispute even about who was making this claim of Jesus’ supposed craziness or mental instability: Was it his relatives or the scribes, whose opinion of Jesus was reported in the next verse?

Mark 3:22 And the scribes who came down from Jerusalem said, “He is possessed by Beelzebul, and by the prince of demons he casts out the demons.” (cf. John 10:20-21)

Context highly suggests, in my opinion, that “people” (or “they”) in Mark 3:21 is indeed specifically referring to the scribes, since we know that they thought he was demon-possessed. They alone are described as having this utterly hostile view, not the masses, who, except in Nazareth (Matthew 13:57), and Chorazin and Bethsaida (Matthew 11:21), generally were open to Jesus and his message.

In this understanding, the text is simply construed as his family coming out to remove him from hostile enemies, who were massively misunderstanding him, accusing, and perhaps becoming violent (as at Nazareth, when his critics tried to throw him over a cliff). Hence, there would be no necessary implication (in this particular passage and incident) of his family’s (let alone Mary’s) disbelief in him. They were concerned for his safety.

It’s not just Catholics who think the reference was not to Jesus’ family. Johann Albrecht Bengel (1687-1752), a Lutheran pietist clergyman and Greek-language scholar known for his edition of the Greek New Testament, commented in his Gnomen:

ἔλεγον (they were saying) the messengers [not the relatives] from whom his relatives heard of his earnestness.

ὅτι ἐξέστη (he is beside himself). By this word they were attributing to him excess of ardor, overwhelming his intellect, but it was falsely that they attributed this to him, as Festus did to Paul; Acts 26:24, Thou art mad.

Even in the translations that have “they were saying,” etc. (as very many do), it’s a question of who “they” refers to. It can still be read as others besides the family. The 1953 Catholic Commentary, edited by Dom Bernard Orchard, has some very good commentary on the passage:

The usual interpretation is that relatives (or followers) of Christ, disturbed by reports, came out to take charge of him. The following points are to be noted. (1) The phrase οἱ παρ’αὐτοῦ does not necessarily mean relatives (friends). It has a wider usage which would include disciples, followers, members of a household. It is not certain that the persons designated by this phrase are the same as ‘his mother and brethren,’ 31. Even if they are, there is no reason for thinking that our Lady shared in the sentiments of the others, though she would naturally wish to be present when the welfare of her divine Son was in question. (2) ‘For they said’, rather, ‘For people were saying.’ If this be correct, then 21b refers to reports which reached Christ’s friends, not to an expression of opinion by them.

I readily grant that it’s certainly possible that some of Jesus’ relatives — thinking with the carnal mind that virtually everyone possessed before Pentecost — may have vastly misunderstood him. If so, nothing in that contradicts what Catholics believe. We know that there was some unbelief among his relatives (“For even his brothers did not believe in him” — John 7:5). But this doesn’t include Mary, nor can any passage be found that directly implies any disbelief in Mary about her Son and his status as God Incarnate and Messiah. She knew about that from the time of the Annunciation.

“Unbelief” in Jesus — in any event — was common before the indwelling of the Holy Spirit at Pentecost, and was frequently exhibited even by his disciples. So it ought not surprise us in the least that some of Jesus’ relatives fell into it (including possibly in the passage under consideration).

But this accusation made about the Blessed Virgin Mary in particular is sheer speculation based on an unimpressive argument from silence. It would be like saying, “The 12 disciples all believed in Jesus and never ceased doing so.” We know that one, Judas Iscariot, ultimately did not. Or, “No disciple ever doubted that Jesus was risen after hearing reports that he was.” Again, we know that Thomas did doubt (John 20), though it was short-lived. One can’t determine all particulars of beliefs of those in a group, with sweeping statements or mere speculations.

Likewise, by the same logic, one can’t determine even from this variant rendering of Mark 3:21 (“When his family heard about this, they went to take charge of him, for they said …) — a rendering I don’t accept — that Mary, who is mentioned as being with them 10 verses later, was included in this opinion. There’s simply not enough information. It remains an argument from silence. We could know this for sure only as a result of a biblical passage (if there had been one) like the following: “When his mother heard about this, she went to take charge of him, for she said, ‘He is out of his mind.’”

Anyone is at the very least equally justified in believing that she did not think that, as they are in thinking that she did. We don’t have enough information (here or anywhere in the New Testament) to decisively assert that she thought negatively about Jesus. And that remains true about Mark 3:21 regardless of whether one thinks that Mary was sinless (as Catholics do) or not. It’s a matter of logic and exegesis. The burden of proof is on Protestants to try to prove a “sinful or unbelieving” Mary.