The words "struggle" and "work very hard" mean basically the same thing. Paul uses them together to emphasize the intensity with which they serve God. (See: [[rc://en/ta/man/translate/figs-doublet]] and [[rc://en/ta/man/translate/figs-metaphor]])
The understood information can be stated clearly. AT: "but he is especially the Savior of those people who believe" (See: [[rc://en/ta/man/translate/figs-ellipsis]])