St. John Chrysostom extols the importance not only of intercessory prayer, but also in the local Christians assembling together to petition God for various needs. Taking as an example a king who is not moved to commute a death sentence when one person petitions for clemency, but then is moved when people gather together to intercede for the condemned. In his example, we may see how public opinion could even sway emperors and despots. Such influencing leaders is not the invention of modern media or democracies, but has been practiced since ancient times.
Likewise, too, in the case of a king: in many cases after consigning someone to death and not responding to one person’s appeal for the condemned, he is importuned by the petition of the whole city, and the man taken off to the dungeon he snatches from condemnation on account of the huge number of petitioners. and returns him to life.
Such is the force of the intercession of the multitude. This is the reason we also all gather here, to win God over to mercy the more readily: since in praying by ourselves, as I said before, we are weak, bound together in love we importune God to give us what we ask. Now I do not say this idly or for my own sake alone: it is for you to be ever prompt in attending the assemblies in case you should say, Why? can I not pray at home? While you can pray, prayer does not have the same force as when it is done with its own members, as when the whole body of the Church with one accord sends up the petition with one voice, with priests present to offer up the prayers of the whole congregation. (St John Chrysostom Old Testament Homilies, Volume Three pgs 35-36)