Synopsis of the Books of the Bible, by John Nelson Darby, [1857-62], at sacred-texts.com
In Psalm 50 we enter on new ground God's judgment of the people. Jehovah the mighty God summons the whole earth; as in Psalm 51 we have their confession of killing Christ.
The introduction of Psalm 50 is magnificent, but requires little comment, God shining out of Zion the perfection of beauty. Only remark that the first two Verses (Psa 50:1-2) are the thesis; from Verse 3 (Psa 50:3) is the bringing it about. But heaven is called in to stand by, a witness of righteousness, and the earth; but the judgment is the special judgment of the people. In Verses 5-6 (Psa 50:5-6), He takes up and accepts and gathers the remnant, His "godly ones," who have now entered into covenant with Him by sacrifice. It is in view, I apprehend, of their seeing Christ whom they had pierced, that these words are uttered. The heavens (though in result God be seated in Zion) bring in their display of the righteousness of God; distinct in itself, note, from His judgment. This is general. It is not in itself the judgment of God. I doubt not, He shines forth in glory therein, but in a particular manner. We can say it is the glorified saints who display this, of course with Christ Himself; yea, so fully that they shall judge the earth. It is not judgment through secondary causes: God is now judge Himself hence gathers His saints too. In Verse 7 (Psa 50:7) the people are judged. God does not want sacrifice, He wants righteousness. He will not have wickedness, nor, now, the wicked among His people. So we read in the very same way in Isaiah 48 and 57. Man fancies God is such as he himself is; but all shall be set in order before Him. This is God's judgment.