Jamieson, Fausset and Brown on Micah 7:18

18. Grateful at such unlooked-for grace being promised to Israel, Micah breaks forth into praises of Jehovah.

passeth by the transgression--not conniving at it, but forgiving it; leaving it unpunished, as a traveller passes by what he chooses not to look into (Pr 19:11). Contrast Am 7:8, and "mark iniquities," Psa 130:3.

the remnant--who shall be permitted to survive the previous judgment: the elect remnant of grace (Mi 4:7; 5:3, 7, 8).

retaineth not ... anger--(Psa 103:9).

delighteth in mercy--God's forgiving is founded on His nature, which delights in loving-kindness, and is averse from wrath.