The Entirely Merciful.
The Especially Merciful.
This special mercy of His is reserved for the believers. His mercy being divided in to 100 portions, His attribute Ar-Rahman, which encompasses all the mercy He has showered in this world on all the creatures He's created - animals and birds, believers and disbelievers, the righteous and the sinful, the mercy a mother has for her baby, the mercy an animal shows to its offspring, all of it together makes only one portion of His mercy out of 100. The rest 99 is what Ar-Raheem holds, which is reserved ONLY for His believing and righteous servants for their afterlife.