One characteristic of Mark’s Gospel, as of the others, is that the Evangelist makes no attempt to gloss over difficult parts of the story he has to tell; as the recipients of the Gospels would either have known Jesus, or known those who had, it would have undermined their credibility to have missed out things which others knew. We have one such example in today’s Gospel.
Justin Martyr points out that Jesus pursued the trade of his foster-father, and, as Emphrem the Syrian adds, by that fact blessed all labour. St Gregory Nazianzen takes up the question of what it can mean to say that Jesus, who is God, could do ‘no mighty work there’? This emphasises the importance of faith. God does not act on us as though we were without will, he does not simply compel us (although he could, of course), but rather, he requires of love and our faith in Him; if this is lacking, then though He wants to help us, we will not receive Him. We possess free will, and though God would prefer us to respond to His love with faith, we can refuse Him. So we see, as John Cassian comments, that there must have been some who believed and were healed, but the majority could not see beyond their own pride.
Where faith is wanting, or where we substitute for it what we think we know, then God cannot enter in, not because he is not omnipotent, but because we refuse him. As with Our Lady’s acceptance of God’s will for her, he requires our love and our faith. We grieve him with our hard hearts, hard as stone they are, and sometimes, as Newman commented, they require to be broken before they will receive his seed.