Imagine yourself as a defendant in a court of law. The prosecuting attorney has rested his case and you await the verdict from the jury. "All rise," says the bailiff. You then hear the words every defendant dreads: "Guilty as charged!" What now? Your only hope is that the judge is merciful.
Fortunately for guilty sinners like you and me, the Judge of the Universe is "rich in mercy." God has more mercy than all the millionaires and billionaires in the world have money. Though he is merciful, he is not lenient.
Somebody had to pay the penalty for our sin. Yes, that Somebody was the one who said, "Blessed are the merciful, for they will be shown mercy."