To execute judgment upon all; either upon all the wicked in general, who afterwards may seem to be distinguished into different sorts, or else the Greek preposition kata is put for peri, and the word all is to be understood of all universally, good and bad; and the words may be read, to execute judgment over all, i.e. to judge all.
And to convince all that are ungodly among them: if we take the words in the latter sense mentioned, then he distinguisheth those that are to be judged into good and bad, and the Lord comes to execute judgment over all, having convinced the wicked among them; but if in the former, the ungodly here may be taken for those that are more notoriously so, those that have obstinately rejected the gospel, or wickedly perverted it, or persecuted the saints, &c.
Which they have ungodly committed; i.e. with an ungodly mind, willingly, delightfully, perseveringly.
Their hard speeches; i.e. blasphemous, irreverent, against God, his truth and ways.
Which ungodly sinners have spoken against him; he executes judgment, though upon all the wicked, yet especially upon these ungodly sinners, i.e. that are such both in their words and deeds against him, in his truths, ways, ordinances, people, &c., and therefore are the worst of sinners.