This is a song for vexed and frustrated people, for relatively poor, unnoticed people, for people who won't be helped much by the civil authorities because they're just not important enough (the authorities might even be part of the problem). It's a song intended to bring hope to such people, a song that speaks to them with the voice of God's salvation!
It begins with their complaint. They cry out, "Help, Lord, for the godly man ceases! For the faithful disappear from among the sons of men. They speak idly everyone with his neighbor; with flattering lips and a double heart they speak." Does it sound like modern politics? It should.
Now that the people are 100% with the song leader because their innermost feelings have been expressed, he's able to lead them in a straightforward prayer for practical relief from the oppression. In their prayer they plead with the Lord of earthly governments to rid them of these authorities who have flattering lips (to get votes?). The flatterers speak "proud things," and they flaunt their authority and their high positions. They explain their behavior by telling the people how busy they are and how they can't possibly help every person with every complaint. They say there are other, more important issues that they really must dealt with first.
Not only so, but these so-called "public servants" feel that they can tell these poor people who come to them for help anything they want, because, as they put it, "our lips are our own; who is lord over us?" They have no concept of a real Covenant God Who sees every action, Who hears every word, who knows every thought - and Who CARES.
But the song leader leads the people to sing the sure response made by that loving, caring God Himself. They sing, "For the oppression of the poor, for the sighing of the needy, now I will arise, says the Lord; I will set him in the safety for which he yearns!" This is the sure promise of the Lord God of Israel, a promise He has repeated to them many times, a promise very dear to His heart because these are His chosen, His covenant people.
Such a realization should bring consolation to these troubled people. It should lead them to the conclusion that, "the words of the Lord are pure words, like silver tried in a furnace of earth, purified seven times!" In other words, as they hear themselves singing, they can come to realize that God Himself really IS their Protector! This is absolutely and always true, even though, as they must say, "The wicked prowl on every side, when vileness is exalted among the sons of men."
It's the same in every age, isn't it? Corrupt, godless authorities become hard and uncaring about those under them. But also true in every age is the fact that the Lord knows and cares - and will deal with them. Let us pray even now with the confidence of the psalmist. God has not changed!