The psalm begins with a comparison: those who trust in the Lord are like Mount Zion, which cannot be moved but abides forever. The picture speaks of stability; trust does not make a person stronger but steady, because it rests on something that does not change.
Verse 2 widens the picture: as the mountains surround Jerusalem, so the Lord surrounds his people, from this time forth and forevermore. The city is protected by geography, and the people by the presence of God.
Verse 3 holds a promise and a reason: the scepter of wickedness will not rest on the land allotted to the righteous, so that the righteous will not stretch out their hands to do wrong. Verses 4 and 5 ask for good for those who are good and upright in heart, while those who turn aside to crooked ways the Lord will lead away with the evildoers. The psalm closes with a blessing: peace be upon Israel.