English Basic Explanation - Chapter 125
Chapter 125 extols those who "trust in God," comparing them to the city of Jerusalem. The city of Jerusalem is surrounded by tall, majestic hills, yet it is the Almighty – not geographic features – that will, in the future, eternally guarantee the city's safety and protection. Similarly, one who sincerely places his trust in God can depend upon His grace, assistance and protection, without having to rely on far less dependable sources of safety.
In verse 3, we are given the reason why evil cannot prevail, and why truth and justice must ultimately triumph over corruption and falsehood. The Psalmist explains that if the evildoers seize control over the righteous, they will impose their decrepit moral standards upon their pious subjects. God of course desires a world of honesty and just, upright behavior, and to that end He must eventually see to it that the righteous men of the world are victorious in their struggle against evil and corruption. Indeed, this chapter ends with a heartfelt prayer that God bestow His grace and kindness upon the righteous, and eliminate the evildoers.
This chapter thus speaks of the inevitability of good's eventual triumph over evil. Just as the prophets have promised the eternal protection of Jerusalem in the time of Mashiah, so are we guaranteed that the righteous men of the earth will ultimately succeed and that corruption and evil will vanish.