In Psalm 14:1, who are "they"?:
Psa 14:1 To the Overseer. --By David. A fool hath said in his heart, `God is not;' They have done corruptly, They have done abominable actions, There is not a doer of good.
This is normally considered to be talking about "fools":
They are corrupt &c.] More emphatically the original: They corrupted their doings, they made them abominable, there was none doing good. Mankind in general are the subject of the sentence. Abandoning belief in God, they depraved their nature, and gave themselves up to practices which God ‘abhors’ (Psa_14:6). ‘Corrupted’ describes the self-degradation of their better nature; ‘made abominable’ the character of their conduct in the sight of God. Such was the condition of the world before the Flood. See Gen_6:11-12; and with the last line of this verse, cp. Gen_6:5. P.B.V. follows LXX and Vulg. in adding no not one as in Psa_14:5. For doings Psalms 53 has iniquity:—‘they did abominable iniquity.’ (The Cambridge Bible for Schools and Colleges By Cambridge University Press.)
However, the plural "they" does not agree with the singular unnamed "fool".
Might it actually read like this?:
Psa 14:1 To the Director: A Davidic Psalm. A fool says to himself, "There is no [true, useful, available, good] God. They [ie: "the gods"] are all corrupt and commit evil deeds; not one of them practices what is good."
This not only agrees with the first verse but also makes the rest of the Psalm cohere as a kind of argument between God and unbelieving humanity. God's response to the fool's complaint is to describe himself as despairing of finding a good human:
Psa 14:2 The LORD looks down from the heavens upon humanity to see if anyone shows discernment as he searches for God. Psa 14:3 All have turned away, together they have become corrupt; no one practices what is good, not even one.
He affirms that God is among the congregation of the righteous:
Psa 14:4 Will those who do evil ever learn? They devour my people like they devour bread, and never call on the LORD. Psa 14:5 There they are seized with terror, because God is with those who are righteous. Psa 14:6 You would frustrate the plans of the oppressed, but the LORD is their refuge. Psa 14:7 May Israel's deliverance come from Zion! When the LORD restores the fortunes of his people, Jacob will rejoice, and Israel will be glad.
All quotes are from the ISV unless otherwise noted.