Summary: A court case - with the people of God in the dock.
Taken as a whole, the content of this Psalm appears as a court case, with El Elohim Yahweh, “the Mighty God the LORD” (Psalm 50:1) presiding as Judge (Psalm 50:6) - and God’s covenant people in the dock (Psalm 50:5).
The scene is set with the appearing of God. Our God is the mighty God, the God who speaks, the God of all Creation (Psalm 50:1). The God whose word shines forth from the heavenly Zion, and from the earthly Jerusalem (Psalm 50:2). The God who comes, and is coming, and shall not keep silence (Psalm 50:3a).
Our God is a consuming fire (Psalm 50:3b; cf. Hebrews 12:28-29). He calls the heavens and the earth to attend as He judges His people (Psalm 50:4). Gather My “saints,” He commands, “those who have made a covenant with Me by sacrifice” (Psalm 50:5). “Let the heavens declare His righteousness, for God Himself is Judge” (Psalm 50:6).
The first indictment is about formalism in worship (Psalm 50:7-15). Here the accused are addressed as “Israel”, and are reassured that they are dealing with (literally) “I, God your God” (Psalm 50:7). It is not that God was against the sacrifices altogether (Psalm 50:8) - after all, He had commanded them, and they pointed forward to the ultimate sacrifice of Jesus (cf. Hebrews 10:4-10) - but He was refusing to accept their sacrifices as long as they were offered as bribes, or as long as people imagined that He benefited from them. This is like church people imagining that their attendance at church earns them credits with God, or that their sacrificial giving is somehow them helping God!
The second indictment is about hypocrisy (Psalm 50:16-22). Here the accused are addressed quite bluntly as “the wicked” (Psalm 50:16): “What right have you to declare My statutes, or to take My covenant in your mouth, seeing you hate instruction and cast My words behind you?” (Psalm 50:16-17). “You thought that I was altogether one such as yourself” (Psalm 50:21).
Hypocrisy, play-acting, lurks in many a dark corner in many a church and theological faculty - and in our own hearts. It is one thing to ‘talk the talk’ as the saying goes, but it is quite another to ‘walk the walk’. What good is all our religion if we have not justice, mercy and faith (cf. Matthew 23:23)? The second indictment ends with a solemn warning (Psalm 50:22; cf. 2 Thessalonians 1:8-9).
I am put in mind of another court case, when the Son of Man (i.e. Jesus) comes in all His glory and, as a shepherd, separates the sheep from the goats (Matthew 25:33). He will COMMEND the sheep on the basis of what they have done (Matthew 25:40). In like manner He will CONDEMN the goats - the ones among the sheep who are posing as sheep - on the basis of what they have failed to do (Matthew 25:45-46).
The last verse rounds off the argument with an instruction (Psalm 50:23). In answer to the first indictment, it is the one who offers praise who glorifies God (cf. Romans 12:1). In answer to the second, it is to the one who orders his conduct aright that God will show His salvation (cf. James 3:13).