“שומר ה’ את כל אהביו ואת כל הרשעים ישמיד – G-d protects all of those that love Him, and the evil ones He will destroy.”
The Etz Yosef points out that unlike the false gods of the ancient pagans that had a limited portfolio, e.g. a sun-god, love-god, war-god, Hashem, the King of kings is G-d over all and therefore He is both the G-d that protects His devoted flock as well as the G-d that destroys the wicked.
Many commentators mention the contrast between this verse, “שומר ה’” and the previous verse, “רצון יראיו” The previous verse tells of those that fear G-d, and our present verse refers to those that love G-d. Love of G-d through study, prayer, and action eclipses fear of G-d. Therefore the reward for displaying love of G-d is greater; whereas one that simply fears G-d is attended to dearly, one that loves G-d is provided divine protection – שומר ה’ את כל אהביו.
In the Siddur HaGra, the Siach Yitzchak states that this verse provides an insight regarding the famous theological quandary of “Why do bad things happen to good people?” He explains that the word שומר has two meanings, to guard against as well as to preserve for the future. In our verse both meanings are relevant. While it is true that G-d protects those that love Him, G-d also reserves and preserves the ultimate and eternal reward for the faithful and it will ultimately be presented in the World to Come. This teaches that when evil people seem to be rewarded in this world, the reward is ephemeral; and when righteous people seem to suffer, the suffering is temporary and serves as a refinement process. The ultimate reward and punishment is only meted out in the World to Come.
May we all climb the rungs of the ladder of service to Hashem, learn to accomplish and establish love of G-d, and merit the rewards from our efforts in this world and the World to Come.