1 This Psalm, like others similarly named, was so entitled either from the name of the man who wrote it, or from the explanation of that same name, so as to refer in meaning to the Synagogue, which Asaph signifies; especially as this is intimated in the first verse. For it begins, “God stood in the synagogue of gods”. Far however be it from us to understand by these Gods the gods of the Gentiles, or idols, or any creature in heaven or earth except men; for a little after this verse the same Psalm relates and explains what Gods it means in whose synagogue God stood, where it says, “I have said, You are gods, and you are all the children of the Most High: but you shall die like men, and fall like one of the princes.”
In the synagogue of these children of the Most High, of whom the same Most High said by the mouth of Isaiah, “I have begotten sons and brought them up, but they despised Me,” stood God. By the synagogue we understand the people of Israel, because synagogue is the word properly used of them, although they were also called the Church. Our congregation, on the contrary, the Apostles never called synagogue, but always Ecclesia; whether for the sake of the distinction, or because there is some difference between a congregation whence the synagogue has its name, and a convocation whence the Church is called Ecclesia: for the word congregation (or flocking together) is used of cattle, and particularly of that kind properly called “flocks,” whereas convocation (or calling together) is more of reasonable creatures, such as men are....I think then that it is clear in what synagogue of gods God stood.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)