Jesus reacted with firm and clear words; he did not tolerate this, because those scribes, perhaps without realizing it, were falling into the gravest sin: denying and blaspheming against God’s Love which is present and active in Jesus. And blasphemy, the sin against the Holy Spirit, is the one unforgivable sin — as Jesus said — because it comes from closing the heart to God’s mercy which acts in Jesus.

[Pope Francis, Angelus 10 June 2018]