Perhaps more than any other teaching of the Catholic Church, the doctrine of purgatory sets Catholics apart from other Christian professions. While all Christians acknowledge the Four Last Things — heaven, hell, death and judgment — only Catholics understand that between hell and heaven lies a third, temporary possibility for many souls who, while dying in a state of grace, must still reform their souls — purge them ­— of the residual effects of sin. The reality of purgatory speaks to both God’s mercy and God’s justice, but also and especially to God’s love for souls.